The difference is maybe because IR‘s are already mixed with EQ, filter etc. and Dyna Cab are completely plain without any processing.
Doesn’t matter if you are a live or studio guitarist, when you are recording, gigging etc. with a cab, your sound will always gonna be mixed to the FOH etc.
I can’t remember a situation where a sound guy only places a microphone on the cab and send the signal straight to the audience.
So maybe that’s what’s missing?
The OH IR sounds a lot like it’s been mixed and or filtered.