I don't think that Butterworth is a crossover. Rather it's a filter
A crossover IS a filter. As you know, the xover is there to divide frequencies between drivers through attenuation (dependng upon how strong -- the slope or order -- that attenuation is one speaks one 1st order, 2nd, etc). To expand on the original question would be outside the scope of a post IMO. Suffice to say that each "type" of xover, Bessel, Butterworth, L/R, etc has electrical characteristics other than the order. One place to visit is
here. There is alot of info on the net. Cheers
