Comment by krab

In practice, it works the same.

Technically, there are two kinds of copyright - I'll translate loosely from the Czech law, I'm not sure about the exact English equivalent. There are "person" rights and "property" rights. You can never rescind your "person rights". But that only means that no one can claim you're not the original author. That's about it. You can transfer "property rights" via licensing as you wish. The license can be exclusive and you can give a right to further transfer or sublicense the work to the licensee.

Also, each work is copyrighted by default. You're not allowed to use something that you just found on the internet if you're not granted a license.