As mentioned very early in this thread, what makes a trawler cannot be seen because it is under the water.* GB, OA, Symbol et al like to call something that has a covered sidedeck, Portuguese bridge, staterooms crammed forward, or a forward raked windshield a trawler. Nope, won't cut it in big water and cold weather.
Nor do a bunch of underpowered vessels that couldn't make their minds up between SD or full displacment. Slow does not mean trawler to the purist but has become a common naming in the past 30 years.
Try this for trawler : a deep keel to protect the prop(s), properly shaped stern for follwoing sea safety, 1000 mile cruise range at a minimum, overall sea keeping ability, heavy loads of fuel, water and gear do not affect performance at 8 to 10 knots, engines sized for hull speed plus a very comfortable safety factor, shuns light high speed diesels etc.
Does anybody doubt that a Nordhavn or*Northern Marine are not a trawler? Or the myriad of fishing trollers? PMM notes that many 3000 hp 60' vessels are trawlers; well I don't think so but they are pretty.