Set said:
You may be right, I may not be 'getting' the 4E designations at all.
I was not aware that the Defender was a battlefield controller with no (or limited) reach, and the Controller was a battlefield controller with reach.
Its not precisely the same.
Knocking someone off their feet stops them from moving around the battlefield as much as they'd like. It may also grant attacks of opportunity if someone is nearby to exploit it.
Defenders hold enemies nearby, stopping the enemy from attacking weaker party members, and keeping the enemy within reach so that the defender can pound on them.
Controllers affect, amongst other things, the general conditions of the battlefield, including who may move where.
The general act of "knocking someone down" can fit into either paradigm. If your goal in knocking someone down is to curbstomp them while they're there, you're probably acting as a defender. You're trying to keep an enemy nearby so that you can hit them, and they can't hit anyone else but you.
If your goal in knocking someone down is to, say, stop them from charging your party and keep them at range so that your party can pepper them with ranged attacks, you're being a controller.
To make the first work, you need to be able to knock down enemies within your melee reach, and you need a character who is durable enough in melee to survive having an enemy nearby him, and damaging enough in melee to accomplish something while the enemy is trapped.
To make the second work, you need to be able to trip at a long reach. You don't need much melee durability or damage, since that's not where you necessarily expect to fight.
See the difference? Its not about the tool (in this case, knocking enemies over), its about what you're using the tool to do.