Cycling shoes create a more stable and efficient link between the rider and the pedal.
Clipless shoes use cleats that attach directly to pedals.
This setup not increases power transfer. And also allows riders to pull up as well as push down during each pedal stroke.
To disengage from clipless pedals, the rider simply twists the foot to release the cleat.
Within the clipless shoe range, road cycling shoes have 3 bolts to attach the cleat. MTB shoes have 2 bolts.
In Shimano cycles shoes, 3-bolt road shoes are also called SPD-SL shoes. And 2-bolt shoes are SPD shoes.
Flat shoes do not attach to the pedal but feature stiff, grippy soles that improve pedal contact. These are commonly preferred by mountain bikers and riders who value quick foot release.