I can't really comment on the cranbrook but I was in exactly the same situation as you about 3 weeks ago when I looked at the same two bikes at my local Walmart and ended up buying the DelMar. My decision was based on preference, not a noticable quality difference. I liked the black look better that the champaign colored canbrook, I like the Schwinn brand better than the Huffy brand based on experieces with bikes long ago (I am sure quality is equivelent today), and the DelMar had a rear rack and I wanted the to mount the gas tank on a rear rack.
I have been very pleased with my choice of the DelMar for my first build. The build went together quickly and easily. The only challenge was fabricating a front motor mount I was happy with since I didnt want to drill the frame. I had no issues with the coaster brake arm hitting the sprocket or bolts. The only thing I had to do while mounting the rear sprocket was to trim the coaster brake dust cover so the sprocket fits over it and onto the hub. It took less than 5 minutes and then the sprocket fit perfectly. Other folks have instead enlarged the center hole in the sprocket but trimming the dust cover seems to be a lot easier and cleaner.
Below is a pic of my build that I just finished a few nights ago (bad cell phone picture). I have a few clean up items left such as shortening the cables, etc but she is running great.
Bottom line is there have been lots of builds on both so you will be just fine with either bike. Pick the one you like the best and get on with the building...