Difference between "unselect" and "cancel"-hotkey?

Talking about Settings>Hotkeys>Game Commands> “Cancel” (on the very top of the list) and “unselect” at the very bottom.
Both seem to do an “unselect”-action for me. Is that a bug, maybe?
I kind of expected I could cancel units or technology in production with the “cancel”-hotkey.
(either cancelling, the first, last item or perhaps the entire queue, I don’t know)
That does not seem to be the case.
What’s going on here?

Cancel should stop the current task (such as going to build something), unselect should click off the object. That would be my assumption.

“Unselect” does what you describe. But “Cancel” also does the same thing.
If I want my vills to stop building something, I’d use the already existing “stop”-hotkey.

Cancel is if you have the build menu open, but don’t want to deselect the vil.

No, you are referring to Settings>Hotkeys>Villager Build>Cancel. That’s a different hotkey. And that one works just fine.
I am talking about the recently introduced Game Command hotkeys.