We migrated several years ago. This discussion is bringing back the things that were majorly different. The big thing that I noticed was that while Blackboard is centered around the files you upload, Canvas is centered around the Modules and even more the Pages you create with those files embedded within it. This is particularly useful for online classes, but works as an organizational scheme for in person as well.
Think of each "Page" as a webpage of resources for that days class/ weeks class/ project etc. With the page you can create a series of instructions that utilize multiple, files, web links, YouTube videos etc. So for a particular class day you can have one page that directs students to embedded links to a pdf to read, a video to watch, and then to the assignment they need to complete. And you have the ability to add annotated text in between these elements telling them what to do. Just uploading files doesn't work nearly as well because the Canvas file organization on the back end is horrible, or massively time consuming to set up. And good luck ever deleting files! I have a canvas page for my research lab, and I am forever cleaning out files (that I thought I had already deleted off the server) to open up more space.
I agree that the announcement function is a bit wonky, especially if you have "canned announcements" that get deployed on a standard schedule. I also agree that having to remember to create an assignment for things like "Final course Grade" is minorly annoying. Tip- always make the final course grade worth zero points. Otherwise students will email you and be confused. It's also very difficult, but not impossible to turn off the running grade average. Overall, I like Canvas much more, but it has also been several years since we ditched Blackboard so I'm not sure how much they even tried to keep up.