As for airplanes, DB is right when he said that most trainers are virtually the same. Where you have a choice is whether you purchase a kit, an ARF (almost ready to fly), or a RTF (ready to fly) package. The kit is usually the cheapest, but requires you to assemble and cover the whole plane. Then you need to buy an engine and radio as well. An ARF on the other hand, like the kit, requires you to purchase an engine and radio separately. However, the ARF is mostly finished, only requiring slight assembly. ARF is typically more expensive than a kit, but is easier to put together (and you don't need to buy alot of the tools -- usually only basic household tools are used). Also, an ARF allows you to customize your plane by choosing an engine and radio to suit your needs. Finally, the RTF. This is usually slightly cheaper than the complete ARF package, but you're stuck with the radio and engine it comes with. Most everything you need to fly comes in the box -- plane, engine, and radio. Assembly time is only about an hour.

As a comparison, the following prices are for the same plane:

Hangar 9 Alpha 40 kit: (heh, not available... oops )
Hangar 9 Alpha 40 ARF: $115, Evo .40 2-stroke engine ($80), JR Quattro radio ($150) - total price: $345
Hangar 9 Alpha 40 RTF: $290 (comes with the exact same components as listed above in the kit).

Personally, I went with the RTF because I didn't know hardly anything about the hobby...I just wanted something "easy." Purchasing an RTF meant I didn't have to spend time installing servos, mounting an engine, breaking in an engine (the Evolution line of engines are already broke in and tuned at the factory, according to their manuals). All I had to do was assemble the 2 wing halves and tail section, attach them to the fuselage, and install the landing gear.

I would recommend a RTF solution to a complete beginner, but since you already have exposure to the R/C world, an ARF would certainly be a viable option.

Oh, and welcome to RCU!