So dumb question on this point. What makes a vault powerful? Is it literally the gymnast's physical strength/muscle? If it comes back to the pop then that seems more like a finesse point, but I really don't know the difference.
Well......Since you asked what myou're afraid some people may view as a dumb question, I'll answer with what some coaches may believe is a dumb answer.
I think both are finesse vaults, each with it's own demands on the gymnast. While a yuri requires a turn prior to contact with the board, a tsuk requires the turn between the board and the table. The difficulty with a tsuk is that the "half" turn onto the table needs to finish in a reasonably straight line through the body with all body segments "square" to the hand placement. I've seen very few gymnasts work the positions as they should, even though adding that "finesse" to the vault really helps tremendously.
I think yuri's make it simpler by getting the the turn done before arriving on the board, leaving the gymnast with nothing to do (well, I said it might sound stupid) but to extend into the table and push off. Yuri's classified as a finesse vault, maybe, but I'd prefer to say that once a gymnast has the entry figured out, it becomes a simpler vault.
In a nutshell, you have to "power" an out of square, poorly aligned tsuk just to survive, or you could learn how to do it right and use far less power with an even better result. As far as yurchenkos are concerned.....half of the most common problems found in a tsuk don't come into play because, well hopefully anyways, the turn is done at the end of the run.
Here's a thought.....Mary Lou Retton competed a layed out tsuk full in the '88 games. I wonder what she'd have been able to do 24 years later with today's vaulting tables, springboards, and a round-off entry, Hmmmm....