What's the Difference Between an Immigrant Visa and a Nonimmigrant Visa?

There are two types of visas to enter the United States. One is an immigrant visa where  foreign applicant intends to live in the United States permanently. A non-immigrant visa is for foreign applicants seeking to enter the US for a temporary time to either visit, study, temporary work, etc. 

Immigrant Visa

An immigrant visa is for a foreign individual who intends to live and work permanently in the US. Generally, a citizen or permanent resident family member or a US employer petitions for a foreign national. Some individuals, such as workers that possess extraordinary ability, investors, and special immigrants can apply for themselves. If the petition is approved, it is sent to the national visa center and a US embassy or consulate to continue the process for the beneficiary of the petition. If eligible and approved for the visa, the individual will use that visa to enter the United States. The immigrant will become a permanent resident once the visa and associated documentation is approved by a border patrol officer. 

Nonimmigrant Visa

Non-immigrant visas are issued to foreign applicants who seek to enter the United States for temporary period of time for business, temporary work, education, medical treatment, etc. Most often the foreign applicant applies directly to the US embassy or consulate for a non-immigrant visa but other types, such as work or education visas, require more documentation prior to applying.  

A list of all the non-immigrant visas can be found here in the USCIS website. Please note that an issuance of a visa does not guarantee entry. A border officer still needs to determine an applicant’s eligibility for admission.

Visa Waiver Program

The visa waiver program is a program that allows nationals of participating countries to apply for admission into the United States for a period of 90 days or less for business or visitation without obtaining a non-immigrant visa first. 

An applicant, once in the United States, cannot file an application for an immigrant or non-immigrant category to change their status. They also can not seek an extension of their 90 day stay.

There are a few basic requirements to apply for the VWP, such as having a return ticket to the country of origen or another country. The list of participating countries and requirements of the VWP are listed here and explain the necessary documentation for the applicant.