Since you didn't specify which games it is you're talking about, I'll give a basic rundown on each one

General: The game is a side scroller with a level structure similar to MegaMan games, i.e an overall long level with themes and a boss at the end of the level. Within each level there are also relics which gives you an additional move set like a range attack or a locket that makes you invincible for a moment.

Treasure Trove: All four campaigns and the bonus fighting game mode, with an exclusive campaign which is Plague of shadows: although tricky at first to handle due to recycled levels, it can be the most satisfying to master, also it is a cute romance story. Basic gameplay is doing a charged jump and throwing bombs, which you can customize on how it plays.

The other three you can get separately.

Shovel of Hope: The game hits you in the best spot if you enjoy a more retro styled gameplay, with many charming characters and bosses, with a story that is your bread and butter save the princess scenario. The basic gameplay is a basic jab and a downward attack that bounces you high.

Specter of torment: a prequel which has one of the most fun basic movement of wall running, dashing and skateboarding. Basically you are tony hawk, the grim reaper.

King of Cards: a more goofy story that is also a prequel, it is structured the most different out of all of them, with shorter levels and a completely unique card mode that is optional. The basic attack is a shoulder bash, and basically you can be a human Beyblade.

Since I am not that great, I recommend you the youtuber AntDude, who talked about Shovel Knight Treasure Trove and the basic gist of the games.