This articles explains the difference between an Event and Reservation.
Reservation: A reservation is a booking for one court at one instance in time. For example, if you a user books Court #1 at 1pm on Saturday, that is a Reservation.
Examples may include: A ladder match, tennis singles, pickleball doubles
Event: An event is when you have multiple people that need to sign up and attend.
Examples may include: Beginner Clinic, Adult Mixer, Camps, Classes
Lesson: Lessons would be where an instructor or coach can schedule and teach or you can allow players to book directly by setting up the Book A Pro feature.
Watch this short video on more examples.
It's important to note all are setup differently.
Reservations
Events
Lessons