If you mean reg to bottle threads then nope - they aren't
They should be, but I've seen a few bottles that wouldn't screw onto regs, mailnly because the regs threaded bit was too long or short for the ones on the bottle.
For instance I once tried to put a "generic" bottle on an AIR and it just wouldn't go, slap on the WDP bottle and it's works like a charm.
I think Phillip is thinking of the Fill adapter - which is different on the gov'nair.