usually when someone advertises a horse as a good 4H project they mean that the horse will be easily handled by children. In our clubs in Canada there wasn't technically a "winner" of the project per se. Each person was graded bronze, silver, or gold for each project depending on how many of the project requirements were fulfilled. If you did all the required work you got a gold on your certificate, so everyone could technically "win".
However, there are also shows. 4H horse shows worked the same as as other horse shows are judged and our kids accumulated points from the shows to get "high point" at the end of the year. I don't believe there were halter classes, rather showmanship was the class aside from regular riding and driving classes.
In adition, for all projects (equine, other animal, crafts, cooking, woodworking etc) there are different levels of competion from local to provincial to national where the quality of the project is judged, for horses this is again a regular horse show similar to regionals and nationals where they compete against each counties (or provinces!)high point winners I believe.
So the long and short of your answer is yes, all of the above and each seperate. I don't believe the horses conformation was judged, but other livestock was. I showed rabbits and others showed cattle, sheep, ducks, goats etc etc and all these were shown both showmanship and confomation. Horses were, as far as I remember, just shown showmanship.
OH, and if you have any kids of your own, check out the 4H program. I loved it and it taught me a LOT. There are also regular public speaking etc contests each year!