there are links to the two cases so you can see their exact specifications.
the th10 is a double wide "box" style case, it is all one large compartment.
the sth10 is a tower style case with a "basement" and "attic" for placement of watercooling components. basically you get more room to mount additional radiators. though with the th10 you can place some radiators in the back of the case if you want to do that.
I believe the cpu would be completely hidden in the STH10 as well, especially if you plan on decking it out with radiators, all the cables and the psu itself would be hidden.
it really comes down to personal preference and opinion on which looks better for you at this point. I absolutely love the layout of the sth10, the th10 is really awesome aswell though, but what sells the sth10 for me is the two additional compartments which give it a change of looks other than one large box.
in the end, go for what you like better, the th10 is a great watercooler, and so is the sth10, if you like the th10, grab it up and live happy with your amazing case!