Or as the bikes are different sizes would i have to adjust the position of the cleats when i swap bikes?
Cleat adjustment should not be required, because the cleat position only determines how your foot is positioned over the pedal spindle. If the saddle position and seatpost height are adjusted correctly on both bikes, and the crank lengths are correct, everything should be fine.
As I understand cleat adjustment:
Fore/Aft adjustment: Changes the load experienced by your calf muscles. If you get calf muscle problems (e.g. cramp), consider moving the cleats aft (i.e. move your foot forward relative to the pedal spindle). I believe positioning the cleat a long way forward is only advantageous to sprinters (who need to use their ankle joint to help yank the lower-most pedal round at the bottom of the stroke). On some frames, toe-overlap can be a problem if the feet are a long way forward on the pedal (i.e. your feet will strike the wheel in low speed tight turns).
Interesting stuff on the mid-foot cleat position (starts a little more than 1/3 down the page)
More stuff on cleat positioning
Yaw (rotation) adjustment: May be important if you have sensitive knees. I have Shimano 520 pedals, I installed the cleats pointing straight fore/aft and haven't had any problems. My view is that these pedals have a lot (almost too much) float built in, to the extent that it shouldn't usually be necessary to rotate the cleats much (they have so much float it would be possible to pedal with my heel rubbing the crank without disengaging).
Release tension adjustment: I have mine set as slack as possible. They work fine, even on fixed-wheel, which is probably the severest test available.