The mountain shoe will raise you just a touch otherwise there is really no difference of merit. Actually, a lot of people ride with mountain shoes as it allows one to walk around with the cleats. Some people think mountain shoes are not as stiff as road shoes and, while this might technically be correct it is doubtful anyone here would be able to tell the difference - especially if you are using the larger platform pedals like Shimano SPD-SL's and Look Keo's.