Spouse of a U.S. Citizen.
A spouse of a U.S. Citizen can qualify for an Immigrant visa (green card) as an “Immediate Relative” and can apply immediately. After submitting the application, the whole process usually takes about six to eight months, however, a spouse of a U.S. Citizen can typically qualify for a work permit in approximately four to six weeks.
A U.S. Citizen spouse might qualify for a K-3 Visa. (see link for more information).
There is no quota for this type of visa.
Spouse of a Legal Permanent Resident.
A spouse of a Legal Permanent Resident can apply for an Immigrant visa (green card). There is a waiting period of several years, depending on the nationality of the applicant. This type of visa is subject to a quota.