Fieldpiece anemometer difference

is there a functionality difference between the accessory head anemometer and the stand alone anemometer?

I have read the posts on the STA2, but if I already have the proper stick meter the head accessory is cheaper.

Thanks

i compared the heads to the standalone at one point, and the heads seemed to be a little off.

I like the standalone.....easier to zero, and you have buttons instead of slide switches.