Waterfall and Scrumban take two different approaches to project management so there are a lot of difference between the two.

Scrumban is an Agile development methodology that is a hybrid of Scrum and Kanban, which are development and manufacturing frameworks respectively.

What Is Waterfall Project Management?
Waterfall project management is the most straightforward way to manage a project.
Waterfall project management maps out a project into distinct, sequential phases, with each new phase beginning only when the previous one has been completed.