There are many different styles and types of capo, all with the same end product in mind. However, they do differ a lot. Some are dead straight, to work with flat fingerboards. Others have a radius which approximately matches the fingerboard radius on cambered fingerboards.
The way they attach to the neck varies too, and some are very easy to move up and down, while others need adjustment. Those with a spring for tension cannot be adjusted, so may, on some guitars, squeeze too hard and put the guitar out of tune, necessitating retuning for each position change. But they store easily on the head of the guitar when not being used.
I don't use capos often, but prefer G7,(not the cheapest!) which can be attached with as much or little pressure as needed.
There are many different designs, so it's worth trying several out. Take guitar to shop. Until you've tried them out, you really won't know whether it was hard sell or good sell. The cheapest is a pencil and rubber band - yes, it works - right through to a 'Spider', which takes things to a different level.