>>11117

I don't mean to give a lazy answer, but, honestly, you'd probably get a better description from their respective Wikia pages than from me. It's been ages since I watched the show as well, so my memory is pretty vague by now.

Very simply, Clover is valley girl, Alex is a bit boyish, and Sam is the smart one, though notably not smart in the sense that she fits into the nerd archetype; she doesn't. She is fashional and socially capable like the other two.

Again, though, you'll probably get a better idea from the Totally Spies Wiki.