What's the difference between associate degree and bachelors degree?

an Associate degree is usually a 2 year program
a Bachelors degree is usually a 4 year program
a Masters degree comes after a Bachelors
a PhD (or any other Doctorate degree) comes after a Masters

AA - Associate of Arts
AS - Associate of Science
AAS = Associate of Applied Science

An associate's degree is a 2-year degree awarded by a community college. A bachelor's degree is a 4-year degree, awarded by a 4-year college or a university. Both degrees are undergraduate degrees. Bachelor's degrees awarded in academic subjects. Associate's degrees can be awarded in an academic subject, but sometimes they are awarded in vocational, non-academic fields, like dental hygiene or something similar.

Once you hold a bachelor's degree, you can go on for a graduate degree. The first graduate degree is a master's, which normally takes 2 years to earn but could take only 1 or as many as 3. Master's degrees can be awarded in a wide variety of subjects. The highest degree is a PhD -- sometimes called a doctorate. It can take up to 8 (or even more) years to earn. PhD degrees are what professors at 4-year colleges and universities hold, in their fields of specialization. A professor of Chemistry holds a PhD (and normally a master's, too) in a branch of Chemistry.

There are also graduate professional degrees, such as the JD that lawyers earn and the MD that medical doctors earn.

AA stands for Associate of Arts. It's a 2 year degree in general academic subjects. AS stands for Associate of Science. It refers to a 2-year degree in a science-related field. AAS refers to Associate of Applied Science, which I believe would be for something like dental hygiene.