I don't think brand to brand really translates that well. Many of the Japanese car kits are curbsides (no engine), most US kits are full detail kits (with engines). The other thing to consider is when the kit first came out, the US kits from the 60-70's tend to have a lot less detail than the kits mastered in the 90's or later
I haven't built a lot of Tamiya kits, but I am finishing up an Alpine 1600 and I'd say the detail is quite similar to the better AMT & Revell kits. I've heard the later Lindbergh kits are nice builds too, but I haven't built one yet (only the 1934 Ford PU which is an old AMT kit).
I think where you will find the biggest difference is the fit of parts, rather than # of parts. Quality varies between kits even within the same company so the best thing to get a good feel for a kit is read reviews and ask around to see if anyone has built it. Few kits match the fit of the better Tamiya kits, so expect to do some fiddling, sanding and filling to get a good tight fit on many kits.
I don't really look at the skill levels of kits, I build what I want to build, skill level and brand are secondary to that. If the only kit available of a subject is a snap kit, I'll build a snap kit.