Another difference I don't think anyone has mentioned is that, since abilities use Supplies in Brink, if Satchel Charges work anything like grenades, they will recharge, so you can keep using them.
I think that is correct and that you can only place a maximum of 3 Satchel charges on the map at one time, not that you will be able to do so off the bat. So the Satchel Charge in exchange for ammo supplying yourself or a teammate one time? Interesting.