Fasb Pronouncements

I am a student at the CPA exam, and I know that some positions are called FASB then FAS and a number, and some are FAS and a number. They do not seem to exclude the other (the numbers are not repeated) and there are new numbers and new FAS FAS numbers. What is the difference?

I finished the exam a year ago. There is no difference. Some people drop the "S" and others not. When you speak, you normally leave out, but the proper way to document, it is to include S.