I think a general rule of thumb is, starting at some arbitrary weight, say 50#, every additional pound of draw weight equates to about 1 1/2 to 2 fps with the same arrow. If both bows shot the same grains of arrow weight per pound of draw weight (gpp), they should shoot about the same speed, all other things equal, which they usually aren't.
One would expect a 12# difference in draw weight to yield more than a 10 fps difference, but, as you've noted, the bow designs are very different. The shorter bow is obviously a more efficient design.