between a spinning rod and a casting rod BLANK, say for bass fishing, rod size, weight, etc etc being equal, or nearly so.

The only difference in your example would be how you choose to build it.

Stan Grace
Helena, MT
"Our best is none too good"

Stan is right, the blank doesn't know what it's going to be until it's built. On the other hand, the blank manufacturers tend to make the blanks that they call "casting" blanks a little heavier and more powerful than what they call "spinning" blanks, for a given designation, such as "medium power." But you can build any blank either way (and I've done so) to get what you want.

Tom and Stan are correct. I would guess to say that manufactures just change the modle number of the same blank so the custermer does not get confussed about what blank he or she should use for casting or spining.. To prove this point just look at the blank specs.
Good Wraps bob