B-2 visitor visas are nonimmigrant visas for persons traveling to United States temporarily for tourism, pleasure or visiting.

B-1 visas are nonimmigrant visas for persons traveling to the United States temporarily to engage in business activities such as the negotiation of contracts, consultation with business associates, litigation, and participation in scientific, educational, professional or business conventions, conferences or seminars and other legitimate activities of a commercial or professional nature.

If you wish to work in the United States for a temporary period you will require a nonimmigrant work visa.  You cannot work on a visitor or business visa, or under the Visa Waiver Program (VWP).

Treaty Trader visas (E-1) and Treaty Investor visas (E-2) are nonimmigrant visas for citizens of countries which the United States maintains a treaty of commerce and navigation (9 FAM 402.9-10).  The applicant must be coming to the United States to engage in substantial trade, including trade in services or technology, in qualifying activities, principally between the United States and the treaty country (E-1); or to develop and direct the operations of an enterprise in which the applicant has invested or is in the process of investing a substantial amount of capital (E-2).

In general those wishing to study in the United States require student (F-1 or M-1) visas depending on whether the study is academic or vocational.

Students taking part in an exchange program, and those wishing to take up prearranged employment, training or research in the United States under an officially approved program sponsored by an educational or other nonprofit institution, require exchange visitor (J-1) visas.

With the exception of a Head of State or Government who qualifies for an A-1 visa regardless of the purpose of the visit to the United States, the type of visa required by a diplomat or other government official depends upon the reason for entering the United States.

Government officials traveling to the United States to perform non-governmental functions of a commercial nature or traveling as tourists require the appropriate H, L or B visa, or if qualified, travel visa free under the Visa Waiver Program; they do not qualify for diplomatic or official visas.

The chart on this page contains many different purposes of temporary travel and the related nonimmigrant visa categories available at Travel.State.gov.