"Cories" is generally taken to mean all of the smaller callicthid catfish. The Genuses are Corydoras, Apistodoras, Scleromystax, and Bronchis.
Albino cories are typically Corydoras aeneus (Bronze Cories), but fairly frequently C. paleatus (Pepper Cories - look at the dorsal fin - it's taller in C. paleatus males - body shape is different too), and occasionally C. sterbae (Look at the pectoral fins, the first ray will be bright yellow in an albino Sterbae). I think I have seen albino C. panda before as well, but I have to wonder what the point of that is.
Green Cories are easy to tell apart. If they're obviously bottle green, and they're less than $15 a piece, then they're Bronchis sp., probably B. splendens. If they're more expensive, then they're Green Laser cories, which have yet to be described as a species. I think they're C. cf. aeneus CW007 or something like that. If they're not so green, then they're probably C. aeneus.
Pandas are really neat. They're about 2/3 the size of C. aeneus, and prefer to be in slightly larger schools (6 at a minimum, 8 is better). They are a little persnickety, but not as bad as people say. My group of 6 has bred itself up to 8 adults, and I just saw fry in the marble field yesterday, so I should have more in not too long.
For a first cory, though, I recommend either Albino C. aeneus or C. trilineatus (Usually incorrectly sold as Julii Cories - they're also sometimes more aptly but just as innacurately called Leopard cories). They're both active, engaging, hardy, eat anything, and breed in any moderately well kept tank.
I got my first school of Paleatus on Monday, so I can't really comment on them long term - So far they seem to be beautiful and hardy, and I'm hoping they'll breed for me after their water change this week. I have never kept Bronchis, but my worry is that it's very hard to distinguish the species, and Bronchis britskii gets up to 7", so a contaminant would be a potential tankbuster (this won't stop me from getting them at some point, though)
So to my cred on this - I have kept: C. aeneus (albino)*, C. trilineatus, C. sterbae*, C. metae, C. pygmaeus*, C. panda*, C. habrosus**, C. arcuatus, C. cf. aeneus "Orange Laser", and C. paleatus. * Bred them, ** couldn't keep them alive for love or money.