Tickets are the total number of entries across all your Magic events, in any format.
Tickets are the total number of entries across all your Magic events, in a rolling calendar year. All play counts.
Tickets count the same player multiple times. A player drafts at 6PM on Friday, that's a ticket. They come back for the 9PM, that's another.
Engaged Players are players that join six or more events at your store in a rolling calendar year in Standard, Draft, and Sealed.
For example, if a player participates in all four of your Prereleases and two of your FNM events (in Standard, Sealed, or Draft) in a year, that's an Engaged Player.
Events have a calendar life of one year. After that year, they will rotate out, and the new events you run will help replenish them.
Both Tickets and Engaged Players help determine how many Promo Packs your store will receive for the season.
For stores who are interested in WPN Premium, there is also another metric: Activated Players.
Activated Players are players that join six events in their first year of in-store play. They are very similar to Engaged Players, but the events they join can be any format.
You'll see your Activated Player total in the weekly WPN Update, although it's only relevant if you're interested in pursuing WPN Premium.