I think what you're referring to is something like this:

[Bass]
Sounds tailored to the low end of a song. Often short and punchy, but certain bass sounds are sustainable.

[Lead]
Sounds tailored to carry the main melody of a passage in a song. More often than not used in the mid to upper octaves because it pierces the mix well, and it establishes dominance over the other instruments.

[Pad]
Pads are sounds that can be held for a long period of time, often for as long as you hold down the keys. Think of pads as what strings do in an orchestra.  They are generally subtle in nature, used "in the background" to carry the chord progression along without taking too much place as to override the lead. They can have a slow or a fast attack, a monotone or evolving nature...it really depends on what the song needs. Pads are generally used to play chords.

[Keys]
Generally refers to sounds that mimic the amplitude envelope of a piano. Basically any sound that hits at high volume, then fades away.

[Atmosphere]
These types of sounds are often atonal, meaning they carry little to no harmonic or melodic value. Think of white noise simulating ocean waves for example.

[Percussions]
Anything that's short, that hits hard and fade away very quickly. They are mostly atonal sounds, but that is by no means a rule. There are in fact a lot of real world percussive instruments that are very much tonal. But yeah basically: drum-ish sounds.

[SFX]
Short for "sound effects" (of course). These are the weird sounds. Alien spaceship fly-by. Radio tuning between stations. Gunshots, etc.

Maybe something like this would be useful? http://www.independentrecording.net/irn … isplay.htm Instruments are evocative of pitch and timbre.

As someone who doesn't have a large musical vocabulary, I'm looking for resources that can help me refer to specific instruments in retro game music.  I've found myself diving into retro game music over the past year, but I often have trouble talking with other people because I don't know what to call various instruments.  I'm not exactly sure what I'm looking for, so take these questions for what they are worth:

Are there libraries of common instruments used in, say, NES, SNES or Genesis games that are named for what I could call them? 

Are there articles that take famous soundtracks and discuss how they are put together in terms of their component sounds? 

Even a wiki that lists the prominent instruments used in each track of a particular game would be a start for me.