What they mean? Hmm...
You're talking about the codes like JCDR-SPY-SB or CDR80WPP600SK, right? If so, they correspond to the differences in the descriptions.
You might get silver shiny, you might get silver matte, you might get printable (different types of printable media). That's all for the top surface.
You might get value, you might get professional. That's regarding the quality of the media.
You might get shrink-wrapped, you might get a traditional spindle with a hard plastic re-closable shell, you might get jewel cases.
You might get 100 discs, you might get...countless discs.
I'd go for professional. Top surface doesn't matter too much, since you don't have any kind of printing needs. Shrink-wrapped media tends to get banged around in transit, so go for stuff in the normal spindle (or jewel cases, if that's an option). And hopefully you can find batches of media in smaller quantities than 100. You might not get smaller than 50 pieces, though.