I remember the big water "moccasins" ( just a water snake really) that were dark colored, with a reddish tint. These guys had heads as big as my hand, triangle shaped, but no fangs, and supposedly not venomous. They were up to 6ft long and aggressive. Every now and then, someone would kill one that did have fangs, and supposedly "were" venomous. I don't really know, as I was never bit, but I have definitly been 'chased" by them,ha.
True, all moccasins I ever saw were poisonous, but we called all these big red snakes moccasins too. Generic term. The big rat snake was also aggressive and would bite, but they were non poisonous. I don't miss them at all! ha. I remember there was a big moccasin we called a "stump tailed moccasin", thick, usually under 3ft and had a bad musky smell. Very posionous. The Timber Rattlers had no rattles, but thats wht we called them. During high water from hurricanes, we had snakes all around the yard,house,etc. (70ft above sea level) it was an adventure, ha.