Hi Cocktail,
You can get more detail at http://uscis.gov/graphics/services/residency/employment.htm#anchor20563.
However, it is the resume of eligibility for each category:
Eligibility
There are five categories for granting permanent residence to foreign nationals based on employment skills. If you are an employer and are unsure which employment category applies to the foreign national you wish to sponsor, or if you are a foreign national and want more information on which category matches your particular situation, click one of the employment categories:
EB-1 Priority workers
Foreign nationals of extraordinary ability in the sciences, arts, education, business or athletics
Foreign national that are outstanding professors or researchers
Foreign nationals that are managers and executives subject to international transfer to the United States
EB-2 Professionals with advanced degrees or persons with exceptional ability
Foreign nationals of exceptional ability in the sciences, arts or business
Foreign nationals that are advanced degree professionals
Qualified alien physicians who will practice medicine in an area of the U.S. which is underserved. Read more about this particular program.
EB-3 Skilled or professional workers
Foreign national professionals with bachelor's degrees (not qualifying for a higher preference category)
Foreign national skilled workers (minimum two years training and experience)
Foreign national unskilled workers
EB-4 Special Immigrants
Foreign national religious workers
Employees and former employees of the U.S. Government abroad
EB-5 Immigrant Investors
You can get more detail at http://uscis.gov/graphics/services/residency/employment.htm#anchor20563.
However, it is the resume of eligibility for each category:
Eligibility
There are five categories for granting permanent residence to foreign nationals based on employment skills. If you are an employer and are unsure which employment category applies to the foreign national you wish to sponsor, or if you are a foreign national and want more information on which category matches your particular situation, click one of the employment categories:
EB-1 Priority workers
Foreign nationals of extraordinary ability in the sciences, arts, education, business or athletics
Foreign national that are outstanding professors or researchers
Foreign nationals that are managers and executives subject to international transfer to the United States
EB-2 Professionals with advanced degrees or persons with exceptional ability
Foreign nationals of exceptional ability in the sciences, arts or business
Foreign nationals that are advanced degree professionals
Qualified alien physicians who will practice medicine in an area of the U.S. which is underserved. Read more about this particular program.
EB-3 Skilled or professional workers
Foreign national professionals with bachelor's degrees (not qualifying for a higher preference category)
Foreign national skilled workers (minimum two years training and experience)
Foreign national unskilled workers
EB-4 Special Immigrants
Foreign national religious workers
Employees and former employees of the U.S. Government abroad
EB-5 Immigrant Investors
. Genreally it can take a month for sure .