H-1B.
Specialty occupations (professional), are for skilled employment, defined as work requiring a university degree or its equivalent in training and experience.
Issued with a validity of 3 years with a max of 6 in total.
Does not require intent to leave after temporary position ends (H-1B does not have to establish foreign residency).
Dependents are admitted as H-4. H-4 spouses may work in some instances.
H-2B.
Non-agricultural workers coming temporarily to perform services of a temporary nature. An H-2B is admitted for the validity of petition plus a maximum of 7 days prior to the validity date of the petition and up to 10 days after the expiration date.
An H-2B must have a foreign residence and must be coming only to fill a position which is itself temporary or seasonal. Dependents are admitted as H-4. Dependents may not work but may attend school without changing status.
H2b is for seasonal or temporary work and is issued for a max of 2 years, but frequently shorter. No route to employer sponsored permanent residence.
The job must be temporary or seasonal
The H-2 visa cannot be issued based upon a temporary job offer for a future permanent position
The employment is “employer specific”, which means that H-2 visa holders are permitted to work in the US only for their petitioning employers
Employment cannot start until the employee enters the US
Employers must obtain from the U.S. Department of Labor a certificate confirming the no availability of qualified US citizens or residents willing to perform the corresponding services
The applicant must demonstrate to the Immigration Service that he/she fulfills the requirements to perform the job
An H-2 visa is granted for a term of one (1) year and can be renew it in one (1) year increments for up to three (3) years
May bring his/her spouse and dependents under twenty-one years of age to the US on H-4 dependent visas
Dependents with the H-4 visa can attend US schools, colleges and universities, but cannot work
H-2 visas are not convertible to legal permanent residence
You must be the recipient of a job offer from a US company to apply for an H-2 visa