"Disbalanced" vs. "unbalanced"

What are the differences in usage between disbalanced and unbalanced?

Well, "disbalanced" apparently is not a currently used English word. It existed but it's not used anymore, since it doesn't appear in the OALD, nor in the NOAD. And when I was editing your question my browser signalled it as "wrong".

Unbalanced is used when you want to define something as not equally distributed, to define a person as mentally ill or disturbed or when someone is "giving too much or too little importance to one part or aspect of something". [OALD]

The Oxford English Dictionary (OED) has an entry for disbalance, meaning to disturb the balance or equilibrium of, to put out of balance. Its derived adjective disbalanced is also included, with a citation from 1885. I'm not surprised that it's not to be found in Alenanno's sources, as it must be rare now, if not exactly obsolete.

Unbalanced is defined in the OED as not balanced or equably poised.

unbalanced means something is not currently balanced and has never been IN balance;

disbalanced indicates something which is not currently balanced but WAS in balance at some point.