The core print quality of both machines at normal speeds is nearly identical. Both are enclosed CoreXY printers with 256 mm cube build volume. The X1C's premium pays for Lidar, which reduces manual first-layer checks, useful if you run prints unattended for hours and can't afford failures. AI failure detection is not a difference: Bambu lists AI error detection (spaghetti, nozzle blobbing) for the P2S too.
Ironically, the P2S is faster (600mm/s vs 500mm/s) because it's a newer platform. The X1C's Lidar does improve first-layer calibration meaningfully, but you can achieve excellent first layers on the P2S with proper bed prep.