802.11B/G Amplifier Question

We're moving an 802.11b setup to an 802.11g setup, and we have a question
that we can seem to find a good answer to. We have amplifiers on some of our
B radios, but we are in the process of removing them by improving the
quality of our antennas and their aiming. A couple still need them, though.

I'm seeing places like Hyperlink advertising 802.11b/g amps in addition to
their 802.11b amps. Is there a physical difference in the amplifiers between
B and G? They both run in the 2.4ghz range, and although the algorithms they
use for handling the signals are different, that's a software-side
difference, correct? Why would they need to different kinds of amplifiers?
Or are we missing something here, like, for example, G could be more precise
in its timing and the G amps are faster to respond?

The only response I've gotten so far is "Our 802.11b amps only work in
802.11b mode. 802.11b/g amps work in both modes," and that's not helpful at
all!

-- Thanks!
Michael Love