Unfortunately, classifications come with mainstreaming. It makes it easier to market a product.
Here’s how I see it:
XC: Long distance, endurance based race format. Typically hardtail or short travel full suspension rigs.
Trail: Our equivalent of “soul surfing”. Short travel to mid travel full suspension or burly hardtail rig.
Enduro : Time trail staged race format. Pedal up in a given period of time. Then it’s a time trial to see who gets down the fastest. Mid travel burly bikes.
All Mountain: What you call enduro riding outside of the race format…pedal up, bomb down.
Freeride: big mountains, big jumps, big bikes. Think Red Bull Rampage.
DH: shuttle or lift to the top of a hill and ride down it. 7-8” big bikes are typically essential but some parks nowadays are dumbed down enough so that a hardtail is all you need to shred. This can be broken down into 3 categories itself: Bike Park, Natural Trail, or Flow.