Atmos and Auro share the same 5.1 or 7.1 ear-level speakers. Both currently use 4 heights speakers, but the difference is in placement.
Auro wants a pair of height speakers on the front wall above the L/R front speakers and another pair of height speakers on the side walls above the L/R surround speakers. By comparison, Atmos wants all 4 of those speakers on the ceiling.
Consumer versions of Auro soundtracks are 9.1 channels (5.1 + 4 heights) or 10.1 channels (5.1 + 4 heights + VOG). VOG is Voice Of God, which is a channel directly above the listener.
The way Denon implemented Auro is strange. If you have 7.1 speakers at ear level and you're playing an Auro soundtrack, then the 5.1 ear-level channels come from 5.1 speakers. Your back speakers remain silent and you can't apply any processing to change that.
Denon allows the front pair of height speakers to be used for both Auro and Atmos, but the second pair of heights can only be used for one or the other. Like I said, strange.
Finally, if the Auro soundtrack is 10.1 and contains a VOG channel, then that channel will come from the 2nd subwoofer output on the Denon. I guess it was used because it contains 100% redundant information (same signal as 1st subwoofer output). DTS is agnostic to speaker layouts. It can render its object-based audio to the Auro layout or an Atmos layout or any speaker arrangement you can accommodate in your room.