I think Paperpgma hit it on the head....beginner classes start with real basics and intermediate and advanced classes assume some basic knowledge of the topic, so you don't have to waste time with going over stuff you will already know such as what foot to use, etc.
Also, each Craftsy class shows you a breakdown of the class before you buy it so if you read through that, you should be able to tell whether you are in the ballpark or not.
Watson