A DAVF is basically a specific type of AVM. It stands for dural arteriovenous fistula and it means that it is in the Dura Mater meningeal layer (involves arteries or veins in that layer) rather than being deeper into the brain.
The categorisation of how/when to treat a DAVF is different from that of other brain AVMs and is often assessed on the Borden scale rather than the Spetzler-Martin grading. (Other scales are available!)
My AVM was a DAVF in my right occipital and whatever artery was involved was busy discharging into my right transverse sinus. I had an embolisation to glue up the join, which, as far as I can tell, was much more of a “shunt” (a direct connection) than the more typical AVM tangle or “nidus” of vessels.