Octa needs time to set up your new track or session, and when jamming, a lot more thought and preparedness in general. Digitakt is much more immediate, which lends itself well to improvising. Especially with simpler music styles like instrumental hip hop or minimal techno, I find the DT more fun to jam with. Sure you might not have all the tools available that you would on an OT, but it can be more fun to make music with “minimal” tools at your disposal (kind of the reason most people do DAWless in the first place, huh?).
As far as the workflow goes, the sequencer is the same and the general UI is the same, meaning that if you’re familiar with a Digitakt the OT shouldn’t confuse you. Or rather, how to use the OT shouldn’t confuse you, but how to make music with one might. It’s both deeper and older than the DT, with some really questionable design choices when it comes to the UI or general architecture of the device. That said, once you get it it’s fairly straight forward and with enough preparation, almost as immediate as the DT. Also MK. 2 has fixed some of the unnecessary menu diving which seems to be what confused most people with the OT.