Difference between subacute rehab and TCU

I've been googling to try to find the distinction between subacute rehab and TCU. Is there a distinction? Or do they functionally overlap?
don't know the proper answer, or if there is one, but i've done clinicals in a tcu and a subacute hospital (not subacute rehab as far as i know). from what i saw, the stay in subacute tended to be longer, like years usually, and there tended to be more trachs and ventillators. in the tcu, i saw pts leaving within days to weeks. again, just my limited experience in two facilities.

Good article describing transitional care for freestanding and hospital based units.http://findarticles.com/p/articles/m.../ai_n18607257/