Tactics vs Puzzles

And in regular speech "do tactics" or "solve puzzles" means the same thing i.e. solve tactic puzzles.
If you think of the options in the app, it's as follows:
The Tactics , as we call it Tactic Trainer, are rating based, so if you solve them you gain tactics points, if you fail, you lose.
Daily Puzzle you just try to solve them. It will not affect any rating, just might be helpful to improve your play.
Lessons is also rating based, and if you solve them without any help you gain some points to your Lessons rating.
Also, you get 5 tactics and 5 lessons a day on the free membership.