So -
Reusable nappies need an absorbent bit and a waterproof cover.
There are All in Ones (AIO) and 2 part nappies.
All in ones are as they sound - the absorbent bit and waterproof cover are all one piece. They come with velcro tabs, and are similar to a disposable nappy to use.
With 2 part nappies, the absorbent bit (inner) and the waterproof outer (wraps) are separate and you can mix and match brands. They can be cheaper than AIOs because you don't need as many outers as inner. You can mix and match brands to some extent too. The inners could be a whole "disposable" shape nappy, or could be a pad that fits into a pocket on the outer. These are called pocket nappies.
I used Tots Bots 2 part nappies to with DS. Then I sold them because we weren't going to have any more children. Then I used Tots Bots AIOs with DD, because we changed out minds about more children and Mothercare were selling off the AIOs really cheap (50% off and 3 for 2).
TBH I preferred the convenience of AIOs, but 2 parters dry more quickly when you wash them.
On top of all this, there are liners (to lift out poo and flush away), which are either flushable or fleece. Using them or not is a personal choice.
Lost of great advice and products at The Nappy Lady.
Good luck and have fun.
If you're not sure about reusable nappies, or like a bargain, google and see if there are any NCT Nearly New sales coming up near you, The Autumn ones will be coming in Sept/Oct, and they always seem to have barely used cloth nappies. Also check your local authority website, some do (or at least used to) do grants for cloth nappies.