Yes, ninjitsu is actually very similar to Jun Fan Jeet Kune Do. Almost like a more traditional version of JFJKD that focuses on weapons more.
It still is’nt a complete martial art though, much like JFJKD. Groundfighting is a little deficient.
In general a ninjitsu man could be called a ninja… but it does’nt sound ‘nice’, sounds like an assassin or something. Anyway ‘ninjitsu’ is simply the slang term for the art. The art is now referred to as Budo Taijutsu(in Japan). But America is a little slow to catch on.. probly because some ninja schools are still trying to cash in on the ninjitsu name.