I use the terms frailing and clawhammer interchangeably. I have heard many different methods of distinguishing between the two.
I recall trying out a banjo in the Toronto Folklore Centre and having another customer say, "I like the way you intersperse clawhammer into your frailing."
I asked him what he meant and he called drop thumb "clawhammer" and "frailing" was when you played only the 5th string with your thumb.
Sandman's definition is that "frailing" is when you brush 2 or 3 strings on the even beats and "clawhammer" is when you hit only one string on the even beats.
In that case, my playing is a frailing/clawhammer hybrid. I mostly hit a single string, but often hit 2 or 3 strings for emphasis. I like to drop my thumb as well.
I avoided up-picking for years, but now enjoy it as well.

A point of interest: When Roscoe Holcomb was a guest on Pete's Rainbow Quest, he played LITTLE BIRDY using Pete's up-picking. When Pete played LITTLE BIRDY on Rainbow Quest, he used clawhammer.
The Greenbriar Boys played a 3 finger bluegrass version of LITTLE BIRDY on Rainbow Quest with Pete sitting in.