It means it's not intended to be permanently mounted. Probably doesn't have a fan or doesn't do well in a "run all night' mode, or is maybe hard to maintain or can't be maintained except via the panel that would be covered by mounting.
Commercial-quality lights tend to, believe it or not, be a bit more rugged.
I wouldn't say one is better than the other, as far as the two you're looking at. I think I was looking at the Mace II a while back. I haven't done any weddings this year, so my needs for high-tech FX is rather low right now.
I'd say if you are choosing between the two, download and watch the videos a few times and see which one seems to peak your interest a little bit better. Either would be fine for mobile applications.