I'm no expert but I would think that if both are equal displacement, the triple may have a little more torque due to larger pistons, the four may be a bit smoother and higher revving. The triple has a nice, diff. sort of sound being of odd number of cylinders. A little more raw if you will.
Yeah, as stated above, more down low torque like v-twin, and top end close to inline 4. Also, they're skinnier than inline 4 in the waist. However, I heard the new 675, it sounds even more high pitched than inline 4, not as throaty as other triumphs I guess.
The Tripple in the Daytona 675 has top end that's similar to that of a 600 class I4, but has a lot more low and mid range power.
If you're talking about the liter Displacement Tripples, they have great low end torgue (They're wheelie monsters,) and really good mid range, but no where near the high end that the 4s do. They sound awsome though. There's no mistaking a 955i, or a Speed Tripple in full song.
The D675 is an all around amazing bike, if that's what you're looking at. Race results this year prove that. Triumph can be difficult to deal with for service from what I hear though.