Just copying this one from the MOMBAT.org blog. Figured it fit pretty easily in both places!
The early Mountain Goats used oval tubing and beautifully finished fillet brazed joints. All of the tubing manipulation and finish work drove the cost of the frames up. The Escape Goat was an effort to bring theses costs down. The frames featured standard round tubing and unfiled fillets. Parts were often less expensive as well with items such as the fork being an off-the-shelf part as opposed to the custom Mountain Goat forks found on the top models. For more pictures, see 1983 Escape Goat page.