Bicycle shoes are designed to maximize the power that is delivered to the pedals by adding force to the pedals onthe upstroke as well as the down stroke. This is especially useful on a climb.
The soles are also extremely stiff with little, or no, flex that would absorb some of the actual power.
They are very light weight. When you think about how many times you lift your feet, on a long ride, you will realize that a few ounces can make a significant difference.
The shoes have a male cleat embedded in the sole that snaps into a spring-loaded female clip on the clipless pedal. The rider is then almost one with the bicycle.
Since most have little, or no heels, so they are not intended for doing a lot of walking.
Road bike shoe
There are different bicycle shoes for road bikes and mountain bikes. The road bike shoes are very light-weight with smooth soles. They typically use Look standard cleats.
Mountain bike shoe
The mountain bike shoes have a heavier tread and more of a heel which makes them a bit easier to walk in. They typically use SPD standard cleats.
What's the difference in the cleats?
If you are going to use clipless pedals,the shoes need to be matched with the pedals so mountain bike shoes with with SPD cleats must be used with mountain bike pedals and road shoes with look standard cleats must be used with road pedals.
The cleats on cycling shoes are either SPD standard (that uses a 2 hole mounting system) or Look standard but there are adapters that allow you to use either.
Mountain bikes use the SPD (Shimano Pedaling Dynamics) and most road bikes use the Look standard pedals that are smaller and lighter.
The mountain bike shoes with SPD cleats can also be used with standard platform pedals.
Road bike riders are usually very concerned with weight and, since they are often riding greater distances, they tend to opt for road bike shoes and road bike (Look standard) pedals.
With bicycle shoes it takes some practice to remove your foot from the pedal, especially if you need to stop fast. You remove your foot from the pedal by twisting your heel outward and, assuming the springs on the pedals are adjusted properly, it isn't hard to do but it does take practice.
I use mountain bike shoes with SPD cleats on my road bike and my hybrid. If I don't want to clip in I just change my pedals to the regular platform pedals. This only takes a minute or so.
A lot of boomers prefer the mountain bike shoes since they are easier to walk in and look more like sneakers or walking shoes.
I don't use clipless pedals and shoes on my recumbent and I don't
recommend doing so. You are usually sitting so close to the ground that
you don't have time to un-clip if you start to fall for any reason.