Look at the handguards.
The cheaper one doesn't have a full pic rail on top, and has three screws where it clamps on.
The higher priced one has full pic rail, two screw at the clamp, a different pattern on the tube.
I couldn't tell you why they are priced $90 different though. Maybe it just depends what PSA had to spend on their materials to make them. Market prices for steel and aluminum going up and down?
If you look, the cheaper one has no T marks on the rail and no logos.
