I own both. They are very different in very many ways, it's kind of tough to compare.
The AD-10 is a full custom knife, it's not CNC machined. That makes for the uniqueness of each one. No 2 are exactly alike as far as I've seen. The lock is of course very strong, and the tolerances are extremely tight. There is literally zero wiggle on the knife in any position or in any direction. There are a lot of features you can have on the knife, steel, handle material, coated blade, etc.
The XM-18 is one of the most well made midtech knives I've ever used. The fit and finish is just about perfect on the 2 I have. The quality is consistent on the various pieces I've seen. These will run in batches, you get what you get as far as steel and blade grind goes.
One thing to remember is that most people that pay this much for a knife will have a lot of reservations about using it. Yet they still ask questions about how strong the locks are, how tough is the blade, and they will probably never even attempkt to cut so much as cardboard with it for fear of "ruining" the knife. To that I say, it doesn't matter how strong the lock is or how tough the blade is if it only gets looked at and fondled.