Okay, what are the differences meant to be? Even if they don't really exist outside of marketron world. And your answer (thanks, btw!) suggests that XC bikes are a bit different from the others - how? I really have no idea - the names, apart from downhill which is obvious, say nothing to me.
As a very general guide, and these factors still vary dramatically between models and rider preference:
Cross country - on the whole now run 29er wheels, have steep head tube geometry (70 degrees +), longer stems, longer top tubes, longer cranks, gearing varies but often you will still see double set ups, be very light. Travel will be 80-100 mm on the front for race bikes, maybe up to 120 mm. May be full suspension or hardtail. All but the cheapest tat will be running air shocks. Normally come with fast rolling race tyres. As lightweight as possible. 20-25 lb.
AM/Trail/Enduro - May be running any wheel size, although many of the best riders I know seem to like the bigger wheels when they have actually ridden them. Have slacker geometry - aroun 67 degrees ish. Very short stems. Wider bars. Average cranks. Travel will be 140 to 160 with 170 on some of the bigger enduro bikes. Usually have a lot of settings on the suspension to set up for varying terrain, but with 'brains' or other overrides on the top suspension for those times you forget to turn the lock out off and start descending. Dropper seat posts tend to come as standard now. Most people set trail bikes up tubeless. Run all round style tyres, but normally on the more aggressive side. Normally 1x10 ot 1x11 set up with a huge range cassette (10-42). Weight anywhere between 28 and 32 lb - some heavier. Normally full air suspension now.
DH - Still very much 26 and 27.5 sized wheels atm (industry fear about 29er wheel strength or just marketing? Who knows, the industry has a lot to answer for). Wide bars, very short stem, short cranks for ground clearance, very long wheel base, low bb height, slack geometry to 64 degree head angle, normally close range cassette (road race style) single ring up front. Big travel 180 mm front and back. Grippy duel ply tyres but, in myexperience rarely set up tubeless due to burping risk as high speed G-Outs (still want to do mine tubeless anyway). Weight anywhere between 35 and 42 lb. Strong heavy wheels. Strong everything really. May still be running coil suspension although air has got amazingly good lately so changing.
