Don't have an answer, but I'm quoting this cause I'm wondering the same exact thing.
It's similar in a way. Whereas the first two games have a heavy GBA inspired chibi art look to them (the original was made in RPG maker)
Very Visual novel centric with key choices offering bad ends, good ends and whatnot. The characters are your common anime tropes, but they work nicely in terms of the story and plot.
Corpse Party 1 is the strongest title by far, and can be played standalone while ignoring the rest of the games. It's very well written, and very well paced game with lots of gut wrenching moments and some highly disturbing content. The setup of the "school" they are trapped in is also very unique and is a key component of what the later games follow.
Corpse Party 2 is not a sequel in a traditional way...its more of an expansion of the first game, giving you an insight in correalting events happening along side the events from the first game and expanding on the story and characters in interesting ways and basically one long set up for Blood drive.
Blood drive is the final entry in the "First chapter" of Corpse party. And it does a good job IMHO of bringing all the elements of the first two games together and meshing them into a cohesive plot.
Note: The actual Corpse Party 2 takes place AFTER the events of Blood drive which was released on PC a while ago...but will be getting an "Official release" later.
Basically if you liked Death Mark...you will definitely enjoy Corpse Party, however without all the translations issues I encountered in DM (there are alot)