An immigrant visa (also called a green card) is for those who want to work and live in the United States permanently. There are two kinds of immigrant visas, those based on a family relationship and those based on an employment relationship. If you want to come stay in the United States to live and work permanently talk to an immigration lawyer to see what options you may have. Not all family members qualify to apply for a visa (for example, an aunt cannot apply for an immigrant visa for her nephew). Nor do all jobs qualify for an immigrant visa.
Non-immigrant visas are for people who want to work or visit here temporarily. While everyone who receives an immigrant visa is allowed to work without any additional permission, the same is not true of non-immigrant visas. Some people who hold non-immigrant visas are allowed to work and others are not. If you are here on a non-immigrant visa and want to work, check to see if you have permission first. If you work on a non-immigrant visa without permission you may be subject to deportation. The most common kinds of non-immigrant visas you may have heard of are student visas, tourist visas and visas for agricultural workers. There are over 15 different kinds of non-immigrant visas! If you want to come here to study or visit, talk to an immigration attorney to see what options you may have and to be sure you apply for the right visa for your needs.