A match is an agreement between two (or more) players to play a match. It could be a league match, a tournament match or simply a friendly match.
A court booking is a reservation of a specific court at a specific time for some purpose. Mostly, the purpose will be to play a match (but could also be, for example, a coaching session).
So you can have a match set up without (yet) having booked a court to play it on. You can also book a court without necessarily declaring what match you wish to play on it.
Tournament and league matches are set up independently from you (by the league or tournament organisers) so they typically will be unbooked to start with. Through the Booking centre you can then choose one of the matches to play in a particular court slot.
You can remove a booking which simply takes away the booking time for a match but keeps the match so that you set up another booking for it. This is different from cancelling a match which is saying that you do not intend ever playing that match. Once a match is cancelled you can't book it. To do so you would have to reset its status to pending (accessed via the change button in the match display) before being allowed to rebook it.
You normally set up a friendly match at the same time as booking it. It is unusual to have a friendly match without a booking but not impossible. It would simply mean that you have every intention of having a friendly between yourself and another player but neither of you have yet agreed a time to play it.
When you invite with a booking, you have the scenario of a booking without a match. When some-one accepts your invite they do so in a specific context like a league match or friendly. The booking and the match are then joined up as a result of the invite acceptance.
When you invite without a booking then the booking is only made when someone accepts your invite and, at the same time, chooses the court on which to play. As above, both the booking and the match are then paired.
Here's a schematic: