F2P is a different approach to gaming where you play the game for Free so no monthly fees and most of the time no need to buy the game, this way you can attract even more player.

Here's a quick example for an F2P MMO with PVP and the difference between both models :

You can have F2P (free to play) games where there's no P2W, meaning the progression is EQUAL for paying and non paying players, the only difference is that you can buy aesthetic items which change how you look, buy extra storage space,etc but give no real advantage other than looking cool or giving you very small benefits.

In P2W model, the way to progress through the game is that you can purchase in-game currency with real money and unlock special items , stronger powers, blessed items (if you die in PVP you won't lose everything), experience booster while leveling your character,etc these items give you an edge over non paying players, so if you stack all the paying items you basically win every fights against non paying players. Therefore no matter what you do in this game you MUST pay to compete.