Types of Bariatric Surgery

Currently, there are three bariatric/weight loss surgeries that are considered the standard of care in the United States.

GASTRIC BYPASS/ROUX EN Y
The most commonly performed weight loss surgery is the Gastric Bypass (aka Roux-en Y), which is both restrictive and malabsorptive. 
The surgery is usually done laparoscopically (through several small incisions versus a large one down the entire abdomen). The stomach is stapled off at the upper portion of the stomach, making a small 'pouch' to hold food, rather than an entire stomach. The pouch is connected to the intestines for the food to continue through the path from mouth to out (esophagus to intestines). The original stomach is completely 'bypassed' (hence the name), since the food goes through the newly created pouch instead. This is generally viewed as a non-reversible procedure, though the surgeons at my hospital said it is possible to be done, however it is very difficult and contains much more risks (so don't count on ever having it reversed when you're trying to make your decision in terms of type of surgery). 
Weight is generally dropped the fastest with this surgery, approximately 18-24 pounds a month (according to my hospital, Memorial in Springfield, IL). However, since the stomach is being bypassed, your body cannot absorb all the nutrients of the foods you are consuming and you will be on specially made vitamins for the rest of your life. These vitamins are specifically for gastric bypass patients, as over the counter vitamins will not be absorbed properly (like the food). 
A common problem post surgery is 'dumping'. This is described as being a painful experience which typically occurs after consuming fatty or sugary foods, but can also occur from other foods. Other symptoms of 'dumping' include abdominal cramps, sweating, fast heart rate and nausea (Memorial). 
I do not feel legally comfortable listing the possible surgical risks, since I am not a medical physician. I would strongly encourage you to research this online (there are tons of credible websites available) and speak with a surgeon and/or his bariatric team about these risks. While YouTube.com isn't really a credible source (people are always more likely to blog, vlog, or comment about the negative as opposed to the positive), there are many people who vlog (video blog) regularly. One of my favorite Gastric Bypass vloggers is saphre1964 (click here to visit her channel). She is a nurse, which aides in her ability to better explain medical things to her viewers, and she always takes the time to answer questions. She posts the good, and the bad. The best thing of all, her personality will always brighten your day. YouTube also has various short videos to show the procedures of various weight loss surgeries. 
Below is a link to one that is computer animated, although there are also many that show the actual organs if you prefer.
Click Here to See a Computer Animated Clip on the Gastric Bypass Procedure

LAP BAND
The Lap Band is a far less complicated (in my opinion) procedure. There is no cutting of any organs. Instead, a silicone band is placed around the upper portion of the stomach. There is a small tube trailing off this band to a 'port', which is placed directly under your skin. Doctors will access this port with a needle and add saline solution, which then travels to the band. The more saline that is added, the tighter the band will be and the more restrictive. 
My hospital's surgeons had told us (in a support group meeting) that you cannot easily feel the port or see it, however, many people online had reported being able to feel and sometimes see their port, giving them some lack of confidence. This band can be removed, however I have heard that insurances do not cover the removal (I cannot speak for all insurance companies, so talk to yours about this). 
Usually, when the final goal weight is achieved, all saline solution is removed from the band and the band itself is left in place (with no restriction). 
There are many horror stories on the internet about this procedure, but keep in mind that more people will complain more than they will praise. Personally, my aunt has gotten the band several years ago (enough for any inflammation to have gone down after surgery), and still has an extremely difficult time keeping food down. I have heard (via internet) that many lap band patients end up having it removed and getting a different bariatric surgery. In my support group meeting, our surgeons agreed with a patient who had said she heard that in Europe, more bands were being removed than put in and she didn't think lap bands would be around much longer. The Lap Band is restrictive only; there are no issues of vitamins not being absorbed. I was also informed (via my hospital, Memorial), that the Lap Band is a procedure for those with less weight to lose (compared to those getting bypass. I cannot find the information that stated the BMI ranges they went by to determine if patients were in the 'range' for the Lap Band or a different surgery, such as the Sleeve or Bypass).
Click Here to See a Computer Animated Clip on the Lap Band Procedure

GASTRIC SLEEVE/VERTICAL SLEEVE GASTRECTOMY
This is the procedure I have chosen, and I may be a bit biased, but I promise I am sharing what I know (other than serious surgery risks, which I feel legally uncomfortable with sharing and believe you should speak with a medical team about these risks, especially since each person has their own medical history which may give further possible risks).
The gastric sleeve is also performed laparoscopically unless there is a certain reason why the doctor opts to perform the surgery open abdomen. The reason for this (laparoscopic) is because there is a less chance of infection.
During a Gastric Sleeving, the surgeon staples and divides the stomach, removing about 2/3 of the original stomach, leaving you with a tube or 'sleeve'. The extra portion of the stomach is removed (as in pulled out of your body and discarded), and therefore the surgery is irreversible. The portion of the stomach that is removed contains a hormone (Ghrelin) which makes you hungry. This doesn't mean you will lose your cravings (that part is in the brain), but you will lose your appetite (for the most part).
There is no 'dumping' with the Sleeve, as there is with Bypass. You must be held accountable for the things you eat (high sugar, high fat, etc). Your stomach could very well stretch out in size again, as it had before with your original stomach.
The Gastric Sleeve is a 'newer' procedure. It relies on restriction, however, your doctor may have you take bariatric vitamins anyway as more research comes in over the procedure. I've heard of people not needing to take vitamins, but my bariatric team does require it (hey, it's better to be on the safe side). 
There are not nearly as many Gastric Sleeve vlogs as there are Gastric Bypass and Lap Band, unfortunately. Click Here to See a Computer Animated Clip on the Gastric Sleeve Procedure (with audio)
However, there is a gastric sleeve specific forum. It can be viewed on your computer or download the app for free to your iPad or iPhone! Click here for the Sleever's Forum!

On A Final Note
You really need to do your research and speak with your bariatric team about your options. See if there is a local support group, where you can meet 'before' and 'after' patients who are more than willing to tell their story and answer questions. There are also a variety of forums online as well. This blog will share my journey with you: information I've learned, going through the prepping stages, recovering from surgery, excess skin and scarring, and of course... recipes that are healthy AND good (and I'm a picky eater so you know it's got to be good!)

On the note of vitamins.... there may be local places in your area that sell these special bariatric vitamins, but there are also sources online. Stay tuned for more information on vitamins, post-surgery approved protein shakes (and liquid diet), etc! 

If you have any questions regarding the information I've given above (or anything else for that matter), please do not hesitate to ask!