I think Andre's system is very useful, and I've never found it confusing. I think that's because I define the #3 and #4 categories by texture. When you try to define them strictly by curl size, there is overlap, and it gets confusing.
To me, type 4 is kinky, and type 3 is a silkier texture. This is usually self-evident (in my opinion), but the easiest way to identify kinky vs. silky is when the hair is blow dried. The type 3s will be shinier and smoother.
I see people getting all confused and hung up on whether their curls are pen spring size, pencil size, or chalk size, and I think all that is unnecessary.
I always thought that 4bs have plenty of curl (tight coils), but no curl definition, since their coils are all headed in different directions. 4c/4z doesn't really have coils, since the hair bends at sharp angles (zig-zag pattern). And 4a has a definite curl pattern, with a kinky texture. I know these aren't necessarily the standard, accepted definitions, but they work for me, so I'm never confused about hair typing.