IMO...it's only confusing when users refer to different ID markers which may reflect the same RAM.
There is an ID number...a part number...a module number...a brand, etc.
The fact that vendors drop obsolete inventory items...doesn't help unknowing users looking for support data.
I just go by the designated RAM speed and module capacity, after reviewing the motherboard specs...and try to buy pairs at the same time, rather than mixing. 2 2GB mods is enough for my systems. I don't overclock or otherwise spaz out over timings, etc...I am not trying to wring the best possible performance from any of my systems...other than to keep them running