Yes the are effectively the same. Same database, libraries etc. You can open Allegro files in OrCAD and vice versa. OrCAD PCB Editor is a cut down version of Allegro PCB Designer. Since 16.5 there is no longer L, Performance, XL. The Allegro PCB Designer is effectively Allegro L + Performance plus other bits from XL. There are add on's called Miniturization, High Speed, RF.
OrCAD PCB Editor has two types, Professional and Standard. Standard has no auto-router, no electrcial constraints, Professional has auto-router, diff pairs, total etch length, constraint regions. Here's a comparsion chart