The big difference is going to be your ability to hit the sweet spot, and get all the distance out of the club. Blades have a smaller sweet spot, but that spot is sweeter then any cavity-back which have a bigger sweet spot, however not as sweet. (if any of that makes sense)

This is from my site that talks about the differences:

CLUBFACE OFFSET
This is the amount of distance that the impact faceplate of the club is placed at or behind the shaft entry point to the clubface. (Phew!) Offset clubs allows the ball to be struck with the hands and shaft more ahead of the ball which is a good thing since you want to use all the mass accumulated during the swing to be used at impact. The minute you flip the hands closed to cause the face beat your hands to the ball, you loose the mass of your hands and shaft that you could have had because the face is the only thing making contact with the ball. Putters are the most common clubs to use this benefit. You always want your hands in front of all shots, especially putts. Flip those hands and who knows how far that ball will go. Players with incurable slices benefit from offset irons and woods because they slice by flipping the hands and the offset "offsets" this and helps the slice.

CLUBFACE TYPE
There are 2 basic types: Perimeter weighted cast iron, and forged blades. I have seen forged perimeter clubs, but not cast iron blades. What perimeter weighting gets you is a bigger hitting area by putting more weight on the outside part of the club face and take away that weight from the middle. Your missed shots are more solid and go farther because there's more weight in the missed area to hit the ball with. Forged blades are less forgiving for the missed shots, but the solid shots are better then the solid shots of a perimeter-weighted club. Better players tend play blades and beginners tend to play perimeter clubs. But that is all up to your preference and style. If you like to move the ball left to right and right to left a lot, it is harder to do the with perimeter clubs because they are designed to counter that action."