hmm....do you mean the difference in games and interiors?
i'll just list the basic points of each tama:
TMGC+C
-in colour, duh.
-there's an "exile" version, and the hexagontchi (like the regular, but you have to answer quiz questions occasionally)
-there are a bunch of locations to go to
-your tama has to shower every couple of days
-trees can be planted
-there are happy items you can find to increase it's happy bar
-there are cute weather animations (more than iD and iD L)
-can remodel house
iD
-the same as the +color, more features (TaMaToMo stamps, ability to transfer downloads via IR)
-lovely melody version is pretty much the same aside from two new characters and games.
iD L
-same as above (in colour, happy stamps, lots of locations, ability to plant seeds for foods and items, lots of characters)
-can also receive downloads via IR]
-there's the 15th anniversary iD L (with Ura characters, pretty much the same aside from a few different characters) and the Princess Spacy iD L, due to be released this month. (you can raise himespetchi and spacytchi's brothers)
i hope this wasn't too confusing for you, if you want to read more check out
THIS page for information about the +color,
THIS page for the iD, and
THIS page for the iD L. good luck on deciding which one to get!