What's the difference between the Tab & Note series?

I've recently been very seriously looking into buying a boox device. I like the idea of having one simple device to handle a lot of my work, but it seems the Note and Tab series are highly similar, and I can't exactly tell why they are separated.

As a side note; I'm asking because I'm unsure which one to really look at. I mainly want to use the device to write notes, read textbooks, read manga, sketch (I'm an architecture student), and make a planner/use other productivity tools. Which series would suit these needs best?