I don't have any experience with the wilderness course.
15 years ago, the older version of OEC, called Winter Emergency Care, was much more winter specific than the OEC course now in use.
OEC now, I'm told, is similar in content and breadth of topics to an EMT Basic course.
You'll get a ton of differing opinions on that comparison. I only put it out there as what I have been told---not what I have experienced, (I never took an EMT course)---to try to illustrate course content.
Although, to be sure, it is less time consuming. For instance, OEC has nothing on motor vehicle accidents, yet it does have heat illnesses and injuries, pregnancies and some limited wilderness content.