The short answer is: too many to tell. 
The more informative answer, there are well over a hundred or so different categories. They are divided into two main groups, immigrant and non-immigrant.
Non-immigrant categories are then divided into families identified by the letters of the alphabet. So there are A-type visas, B-type visas, C-type, D-type, and so on. Every couple of years, law changes require that the list of visas is changed. Currently, the highest letter used is V.
These categories are then subdivided into classes, such as B-2 or H-1
Some classes are further divided. For instance, there is an H-1B and an H-1C (there also used to be an H-1A, but it has been phased out).
Usually, for each status, there is a corresponding visa, and vice versa. There are exceptions, noted below.
Here is a list of all non-immigrant visa families that, to the best of my knowledge, currently exist as of this writing. For a list of all immigrant visa categories, please see the Department of State's Visa Bulletin
| Family | Description |
|---|---|
| A | Diplomats of foreign countries.
|
| B | Visitors.
Most visas in this family are actually issued as B-1/B-2 combinations. This means that you can come to the US either on business or as a tourist, as you like. People who travel to the US on the visa waiver program (VWPP) are also considered to have a B-1 or B-2 visa, but have special restrictions. There is no "immediate family" type for this visa category. Family members simply get the same type of visa on their own. When you apply for either a B-1 or a B-2 visa, you are usually issued a combination visa called a B-1/B-2. This simply means that you can use it to travel to the US either for business or for pleasure, whichever you prefer. Once you arrive in the US, you will only have one or the other status. You will be either a B-1 or a B-2, but not both. Please see the General FAQ for more information about the difference between visa and status. As a special exception, somebody who enters the US as a B-1 business visitor can change to B-2 (tourist) without filing an application to change status. The change happens automatically simply when the purpose of your business trip is accomplished. However, it does not work the other way round! So it would be permissible for you to come to the US for a convention in Dallas, and then spend two weeks in Hawaii on vacation. However, it would not be allowed to spend two weeks in Hawaii first, and then go to Dallas for a convention! |
| C | Transit visa. This is for people who travel through the US to some other destination.
There is no "immediate family" type for this visa category. Family members simply get the same type of visa on their own, with the exception of C-3. |
| D | Crewmember
There is no "immediate family" type for this visa category. |
| E | Treaty Trader
|
| F | Academic student
|
| G | Foreign government officials to international organizations
|
| H | Guest worker
|
| I | Foreign media representative based on reciprocity |
| J | Exchange visitor
|
| K | Fiancee or spouse of a US citizen
|
| L | Intracompany transferee
|
| M | Vocational and language students
|
| N | Relatives of certain special immigrants
|
| O | Workers with extraordinary abilities
|
| P | Athletes and entertainers
|
| Q | International cultural exchange visitors
|
| R | Religious worker
|
| S | Witness and informant
|
| T | Victims of human trafficking
|
| U | Victims of certain crimes
|
| V | Some spouses and minor children of Green Card holders
|
| Special non-immigrant visas | |
| NATO | North Atlantic Treaty Organization
|
| TN | NAFTA visa
|
| TWOV | Status for passenger or Crew Member in transit without visa. This status is also known as C-4. Note: TWOV has been suspended indefinitely after 9/11 and is currently not available. |
| TPS | Temporary protect status. This is similar to refugee status for people from certain countries that were hit by disasters, such as earthquakes or hurricanes. |
| Application Pending | This is a special status that you may have if you file a non-frivolous application to change or extend your status, and your old status expires. For instance, let's say you arrived in the US with a tourist visa (B-2) on January 3, 2003. You now hold B-2 status, usually good for six months, until July 2, 2003. On June 25, 2003, you file an application to extend your status with all the proper paperwork, and a good reason for requesting the extension. That means, your application is not frivolous. In that case, your B-2 status would still expire on July 3. As of July 4, you would be considered to remain in status anyway until USCIS decides your application. Your new status would be "Application pending". Note: this is a bit simplified; there are some additional restrictions that only a competent attorney can explain in detail. |



Nonimmigrant Visa Categories


