In many cases they are. Mainly with drive and suspension. Not much in body and interior parts. I use a nearby Toyota dealer for convenience rather than drive 20 miles or so to a Lexus dealer. My car is a ’97 ES-300 and I start out by asking for ’97 camry parts. ( Incidently the Avalon is part of the group also) I have changed front strut supports, coolant, spark plugs and wires, filters for air, fuel, oil and transmission internal, using Toyota parts. I always brought the old parts in for exact comparison because Toyota uses a different parts numbering system and they evidently can’t access Lexus parts numbers. I think my replacement EGR assy. and throttle sensor could have come from Toyota also but there could be calibration differences as the Lexus V6 makes a little more power. No apparent price differences, but the trip through the Lexus facility does make one feel richer!