Rice rotors use 6 complete rows of bars with 4 bars that have vains that reverse the direction of the grain.

Regular rotors use 3 complete rows of bars and 3 half row of bars with 2 partial bars that reverse the direction of the grain.

On a side note we have replaced the 2 partial bars that reverse the flow of the grain with bars that go in the same direction as the rest of the bars on the advice  of our local MF tech.  Said it would give you more power.  Not a big difference but there is a difference.  If you look on page 388 of the online agco parts book for a 9790 you will see what I mean.

Most of our corn yielded 180-230 bushels and we have no trouble running 4-5 mile an hour with an 8 row head and unloading on the go.   In soybeans its all over the board.  Some sb will cut a lot easier than others.  What I am in now is making 50 bushels and cutting around 4 mph.  They have a lot of green stems.  In sb that have matured right usually the cutter bar is what will limit my speed with a 30 foot head.