Q: What's the difference between mountain bike and road bike shoes?
A: Road bike shoes generally have a triangular three-bolt pattern on the sole that is compatible with most road bike pedals (see image below). Road bike shoes have a very stiff sole for power transfer to the pedals and aren't designed for walking.
Mountain bike shoes have a two-bolt pattern (two sets of two bolts to allow fore/aft adjustment) on the sole that is compatible with most mountain bike pedals (see image below). Mountain bike shoes may also have lugs/tread to assist in walking, but won't be comfortable walking long distances due to the stiff sole.
Active bike shoes typically feature the same two-bolt pattern as a mountain bike shoe, but have the sleek look of a road shoe. The sole is moderately stiff and often includes a rubber tread to aid in walking.