I typically work it out by looking at the labellum. If there are "teeth" running the entire length, it's C. ustulata; if the "teeth" stop half way and the labellum smooths out, it is another species. I can't recall other features to describe moschata other than it flowers later. Many orchids seem to be a week behind last year which probably explains why you have different IDs this time.
C. ustulata have stalked calli on the labellum side lobes. C. moschata have teeth that don't run the full length. It flowers slightly earlier than C.ustulata. As Matt says flowering times seem to be about a week later this year, probably the result of cool damp weather.
I think Tony meant to say that ustulata flowers earlier than moschata, which is why most of the sightings so far this year have been ustulata, and moschata is just starting to appear.