A:
I can't give you cm, because sizes vary for all hooks. If that's what you were looking for, I am sorry, and the following answer may seem elementary for your.
The difference between hook sizes, I can tell you.hooks
Basically 1 hooks are smaller then 1/0 (pronounced one ought.)
Hook sizes go like this, A hgih number (without the /0) is the smallest. I think a size twenty eight is the smallest. As the numbers get smaller, the hooks get larger. A size 14 hook is bigger then a 28 but smaller then a 10. Then, with 1 being the hook without an /0 it goes to 1/0 and then proceeds normally with hook sizes corresponding to number sizes. So a 1/0 hook is bigger then a 1 hook but smaller then a 2/0 hook.
Easiest way to think of it is think of hooks without the /0 as being negative numbers and hooks with /0 being positive numbers, if that makes sense.
(there is no hook size 0