The grille does not determine whether the vehicle is a face lift model, merely a result of the different specifications. To the best of my knowledge some of the grilles are interchangeable between the pre-face lift and face lift models - dependent on the spec of the vehicle of course. The face lift included (but not limited to) a re-design of the front bumper, headlight housing, bonnet, wing mirrors, tail/brake light housing and garnish on the tail gate door.
Pre-face lift GT: https://www.trademe.co.nz/motors/used-cars/subaru/auction-1477284994.htm
Face lift GT: https://www.trademe.co.nz/motors/used-cars/subaru/auction-1478426071.htm
Pre-face lift GT Spec B: https://www.trademe.co.nz/motors/used-cars/subaru/auction-1478927816.htm
Face lift GT Spec B: https://www.trademe.co.nz/motors/used-cars/subaru/auction-1434575354.htm