Those are all very different games. When comparing all of them they only have two things in common, they are all online-only games and they all have micro-transactions.
Destiny (and Destiny 2) is a first/third person shooter action game. At its base it is player versus environment (PvE) with a Player versus Player (PvP) arena mode. You get drops and items directly from monster or arena victories, though what you can get is random. There is character progression.
Fortnite also has two modes. The first is its original PvE mode, which is a blend of Minecraft and Left 4 Dead where a team must attempt to complete a goal in an environment they can both build and destroy as they are attacked by zombies. Forntite loot drops are mostly through loot chests, and it had started to develop a Pay-to-Win reputation. More recently, and an in absolutely brazen move, Fortnite ripped of Player Unknown's Battlegrounds (PUBG) copying that mode into their own game engine to create a PvP mode. Again players are dropped into a destructible and build-able environment with a slowly enclosing wall. Instead of computer controlled monsters, however, the only hostile thing is the other players in a last man standing mode. There is character progression, but only in the PvE mode.
Trove is essentially a mix of a standard MMO and Minecraft. The only thing that prevents it from being just a straight-up MMO is the fact that players can submit content, which if approved, allows them to customize things in the game, or even make new areas. This game is PvE only, and is the most kid friendly of the lot. Like most MMOs there is character progression
Overwatch is a generally a PvP arena shooter, where there is no real character progression. It's primary mode has two teams of asymmetrical characters fighting in direct PvP conflict. There have been other modes, but most of those are temporary and rotated in and out on a regular basis. There is NO character progression in this game, and the only loot, dropped in the form of loot boxes, is only cosmetic.
These games are all very different, each catering to different gamer styles. Of the three Overwatch is the most professional, though Destiny is not far behind.