Both style clutches are centrifugal clutches, as they spin up and gain momentum, they lock up and engage. Bikes do not have disc clutches in them, bikes use a series of friction plates in them that are similar to a clutch disc but not the same. You wont gain mph by switching to a disc clutch, but you will gain some acceleration and your clutch wont get hot as easy or as much as it would with a shoe type clutch. A disc clutch works like this, you have the friction discs, springs, and levers....when the clutch is spinning the levers are thrown outwards which in turn compresses the springs equally, which in turn puts pressure on the discs and locks the discs to the pressure plates or floaters. When the clutch is slipping, the levers dont have enough pressure on the springs yet to compress the discs, so you adjust the engagement a little to make it engage sooner and slip less. When you get to the point where the discs are almost worn out, it will slip at lower rpm's than normal and wont lock up as good, which means its time for a rebuild/refresh of the clutch.
A shoe clutch sort of works the same way, except as the engine spins the clutch up, the shoes start pulling outwards toward the drum until they are locked up to the drum. The drum serves as your pressure plate and the shoes serve as your friction discs if you were to compare a shoe clutch to a disc clutch. With a shoe clutch, instead of turning a screw or adjusting spring height to raise or lower rpm engagement of the clutch, you would change the springs instead. Different spring tensions give you different rpm engagements, which is usually determined by the color of the springs, which varys by different clutch manufacturers.
Hope this helps tell you what your wanting to know, im no expert on clutches but i dont mind sharing what iv learned if it will help someone else learn a thing or two.