Vima is specifically designed to cater to the needs of business teams that work with multiple value streams (types of work) at the same time , and also have to integrate a broad range of date-constrained work.
"Classic" (DJA blue book) Kanban is optimized for teams that do tickets or operate a service with a single, stable value stream. Kanban is focused on managing flow across this single value stream by limiting work in progress and fostering continuous improvement.
Kanban offers practically no built-in tools for managing deadlines, date constraints, recurring work or dependencies. These concepts are a bit orthogonal to Kanban as deadlines and date constraints are not really aligned with the concept of continuous flow.
When managing multiple Value Streams within a single team, Kanban implementations start to falter. Examples of some challenges:
How do you visualize two work types that have different value streams on a single board? The columns are different. You end up with either two boards or a very weird board.
If one work type is assigned to the top row and another to the bottom row, or you have two boards, how do you manage priorities between these two classes of work? It's a bit like a Scrum team with two product owners.
When managing date constrained work, you have to do a lot of workarounds. Example:
Suppose a task is stuck in the first stages of the value stream but has a deadline. There is a risk it will not be delivered. How do you assess and act on that risk? How frequently do you check? When do you decide to expedite it? Even if you manually identify it and expedite it there are no guarantees of delivery as even expedited tasks need to follow the value stream and the priorities (there might be other expedited tasks in your queue, etc). This is all a very ad-hoc process. If this happens regularly, you will suffer. Kanban is simply not designed to handle environments where this happens regularly. Remember, it comes from the car industry.
Vima, by contrast, is focused specifically on finding patterns and working agreements to effectively visualize and manage: multi-value-stream work and date-constrained work.
Vima boards look nothing like Kanban boards: instead of visualizing a complex (multi-step) value stream, in Vima we visualize a calendar and a simple value stream.
Other differences
"Modern" (current DJA/LKU definition) Kanban is incredibly broad in scope, it is not a framework as it does not define roles, meetings or almost any artifacts. This means implementing Kanban correctly requires experience or a coach to guide you. It is not newbie-friendly, even though it tries to position itself as such. This is why you see so many teams with a simple board with 3 columns who should be doing Scrum but have almost no discipline or method and claim they "do Kanban" instead.
Kanban has a confusing leadership, community and intellectual property landscape. It is hard to infer who and what are the official sources of information and updates. There is unclear attribution regarding what is original work and what is derived from Lean.
That said, Vima integrates Lean Thinking and many concepts from Kanban that are useful.