There are always exceptions, but UKC tests tend to be more laid back and gallery-fan-filled than AKC hunt tests. HRC is usually a friendlier vibe. The last dog in the test is called the "beer dog" if you catch my drift. UKC/HRC tests have much more excitement at the line, like in hunting. Multiple guns going off, duck calls, etc. Thus, you can talk to your dog in UKC. AKC tests tend to be more technical (reverse hip pocket marks in senior

) and have more excitement in the field.
At the mid/upper levels, UKC tests tend to have very wide marks, to see if a dog will turn 180 degrees with the gun, and back. AKC tests tend to be VERY tight, to see if a dog will keep from switching. AKC judges tend to cut with marks, UKC judges tend to cut with blinds. Due to the smaller flights in HRC, you don't tend to see flyers, due to the extra expense of having the necessary spare birds to deal with fly-offs. I run and enjoy both HRC and AKC, for the different challenges for the dog/handler team. If you have a dog that can play them both, "you got you a dawg" as they say here!
If you were running under me, I would not say a word for a hand signal to front finish, etc. If you raised your voice, that would be a different deal. I would consider it a compliment to have a competitive dog from another venue running my test!
Go run some HRC tests, they are great fun!