Unfair Contractual Terms under UCC and Common European Sales Law - Confusion Galore!!!

Bhai log, can someone pls clarify the difference b/w unfair contractual terms under UCC and common European Sales Law? I was reading the section 3 of UCC which says that a contractual term which contravenes the provisions of these consumer protection laws or any other law for the time being in force shall be void at the option of the consumer. But then I came across the Consumer Sales Directive of the EC, which has similar provisions, but also introduces the concept of 'detrimental' terms? How does the choice of law clause affect this, and what's the scenario when a contract contains unfair terms under both the laws? I'm completely lost here - need some serious help!