Hey, Linear is opinionated in it's philosophy of Project management and the usage of terminology. We do accommodate all the features that linear has in a general way. Plane is extensible where users can build the framework of their choice.
Height is a very general tool with it's focus on various kinds of teams. With Plane you do that as well. But it's focus is more on the Method. Method or the framework of choice that the team wants to use to manage their projects.