If you look at a surfliner and superliner in comparison, they have the same basic shell and trucks (for SL-II). This probably means the draft gear is the same, windows, end-doors, diaphragms, brakes, a/c units, machine rooms, etc... Paint doesn't mean much.
Pop quiz: what kind of traincar is this?
or this?
They're both actually Superliners in corridor paint, borrowd/bought for CA service because operationally and technologically they are very similar to the California Car. The big diff is doors and seat spacing, and that's because the original Superliner coach was designed to go on 24-hour runs with hours between stops. Corridor cars must keep a much tighter schedule and thus require fast unloading evidenced by 2 sets of double-doors. Heck, there are plenty of corridor runs shorter than your average delay on longer LD runs.
The new Acela: It's not Aveliable.