Confused about UDS dome temp vs. grate temp.

Doing 6 racks of spares in the drum today, set up in an inverted roast rack. Probe from my et-73 is hanging in the vent. I can't remember whether the dome temp is supposed to runs ~50F hotter or cooler than the grate. Tried to search the forum, but couldn't find the answer.

Any help?

Thanks! The dome temps have been running 250ish, the side therm was running 220ish, so I think i'm in the target range. I didn't put the smoker probe of the et-73 on the grate because it was getting in the way, and there didn't seem to be much room for it.