Unfortunately, I think every person on this board will give you a different answer. Here's what I do for both techniques. Call them what you'd like.

Sidedrifting:

You can side drift out of sled or drift boat. The concept behind sidedrifting is that you cast your presentation out slightly upriver of your boat. Don't go below perpendicular. Fish will be taken right next to, or slightly above your boat. The operator of the boat either uses the motor or oars to keep the boat moving as fast as your presentation. Usually, long leaders and very light leads are used on moderate gear. You'll want to set the hook as soon as you feel the fish. It's important that everyone sidedrifting in the boat uses the exact same gear, lead, line, leader, etc. The guy on the oars/motors makes it all happen.

Boondogging:

You really need a motor and a good tracking boat to boondogg (BD). The concept behind BD is that once your boat is tracking as fast as the water you are fishing, all lines are cast well above the boat. Casting well past the bow is not uncommon. Fish will be taken well above your boat. The operator of the boat will take the boat well above where you start to BD. The kicker is started, put in reverse, and the boat is pulled back down the river, as fast, if not faster than the current. The first person to cast out is ALWAYS the first guy at the stern. You work your way up the boat until the guy at the bow is the last guy to cast. Ideally, everyone tries to cast the same distance up river, but tries to hit a different lie in the water. Ideally, you want your 4-5 baits all coming down in their own little path, and not following another bait. It's important that everyone uses the same gear, as if you do not, some one's gear will move faster than others. This leads to tangles, etc. Casting order and discipline is a must here, but not so much when side drifting. Slow action, light rods are used, as you will wait for that rod to "load up" and feel a good 3-4 headshakes before setting the hook. Heavier leads are used to get the baits down. The movement and speed of the boat prevents your leads from getting caught up in the rocks. Like side drifting, the man behind the motor is the key and makes it all happen. Not to mention, since they are always first bait in the water, that rod will almost always hook the majority of fish.

Free Drifting:

Have no idea what this really is, or how it technically differs from the above two.

Like I said, that's what I understand the techniques to be, and that's how we fish those different techniques. More often than not, you'll see a bastadization of both techniques. Very common to see something in between the two on the Cowlitz, etc.

Any ways, I might be full of crap on this one, but oh well. Hope it helps.