Good to see ya again Ghola, how's life treating ya m8? & to keep on topic, yes, there is a difference between the first & second pred's masks. The first mask was very similar to scar's mask from AVP, with all the standard features, & a removable tri-beam laser sight. Pred 2's mask on the other hand was more elongated, with a flatter jaw-piece & a wider eyepiece, also the laser sight was inbuilt into the mask, & was mounted on the left-hand side of the predator's mask, rather than the right, the secong mask also had a much more bronze colouring to it.
Predator: http://www.gothic.no/lostsouls/starscream/predator.jpg (sorry, I couldn't find a better pic at the time)
Predator 2: http://www.physics.hku.hk/~tboyce/sf/films/84.jpg