Spread to pass is what's mainly filtering up to the NFL, from teams like Oklahoma St and West Virginia. Spread to run is actually quite different.
The names give it away, but the spread to run is intended to get fewer men in the box so it's easier to run with it, and is predicated on the read option(s) and inverted veer.
The read option is when the QB reads the backside defensive end. If he stays home, hand off to the running back. If comes forward to go after the RB, keep.
The idea is to make the defense wrong every time. The inverted veer is similar, but very different. Whereas in a traditional read option the RB runs to the strong side and the QB would go to the weak side, with the inverted veer they both go to the same side, with the RB acting as an extra blocker.
This is what Michigan ran to great effect under RichRod, and those two plays averaged almost 9 yards a carry I believe.