[JonPR]

I agree there is too much overlap between the terms to make any sensible distinction. To me, "fingerstyle" sounds somewhat more sophisticated than "fingerpicking", but that's all. "Fingerpicking" has a kind of downhome, country vibe to me. I wouldn't call classical guitar "fingerpicking", but I might call it a kind of "fingerstyle".

Having said that, it's worth bearing in mind that both terms are often used to make a distinction between playing with the fingers (with or without thumbpick or fingerpicks) and playing with a flat pick - "plectrum style" or "flatpicking". And that then depends on the musical culture you come from, it seems. Obviously within classical guitar circles, no such distinction is necessary!

But there are certainly important distinctions between the classical kind of "fingerstyle" and the folk/blues/country kinds of "fingerstyle" - but again there don't seem to be standard conventions in terminology. "Alternating bass" is a type of playing that you tend not to find in classical guitar. (You do sometimes get alternating bass patterns in classical guitar, but very rare.) "Thumb style" is quite a good term, because it underlines how much the thumb dominates in that style; in classical guitar, thumb and 3 fingers tend to be equally balanced.