If you are looking to watch the British Champions Day races from Ascot tomorrow morning, both TVG and HRTV will have coverage of the event. Each channel takes the same feed from England, so it's unlikely they'll be any difference in the pictures you'll see. In past broadcasts of international races (Royal Ascot, Arc, etc), TVG tends to have their in-studio hosts provide some analysis of the action from L.A., while HRTV tends to just roll with the footage coming in from Europe. If you get both, you'll have your choice of American talking heads vs. non-American talking heads.
(By the way, I love the photo of Frankel from the Guineas at the top of this post; the way he strung out that field was beyond impressive. If I get out a magnifying glass I might be able to pick myself out in the crowd (I was in the main stand on the second level, almost all the way to the right, standing at the top of the rows).
Post position times (Eastern/Pacific) are noted below. By the way, take note of the distribution of post times; 35 minutes between all races. No wasting a hour waiting for the next race.
8:50am / 5:50am: Long Distance
9:25 / 6:25: Sprint
10:00 / 7:00: Fillies & Mares Stakes
10:35 / 7:35: Mile (Queen Elizabeth II Stakes)
11:10 / 8:10: Middle Distance (Champion Stakes)