Sedan and wagon antenna, what exactly is the difference?

Can someone provide a side by side photo or details explaining the difference between the two? I've always heard they are different but haven't heard why. The antenna motor is bad in my wagon and I've found a sedan antenna and I'm wondering if I could swap parts around to make one good antenna of the two.

The only thing that looks different to me is the mounting bracket. The actual antenna assembly looks the same. Also the same as the one that I changed out of my 81 Cadillac, and the same as the one that I changed out of mom's 84 Cadillac as well. I have those sitting on the parts shelf in the garage and can take pics tomorrow after work if needed...

Jason.