yes,they're two (or three) different species
Red devils are Amphilophus labiatus - a species from central america.
Most red devils only grow to about 12" or 15" for most larger ones
Red terrors are Amphilophus festae - a species from south america. It's not uncommon for male festae's to grow 18 inches +
(picture just a random one from google)
Theres also another fish sometimes sold as "red terror" or more appropriately "false red terror". - Amphilophus uropthalmus - the "mayan cichlid" from central america - small ones look close to festae so some people take advantage of that to make a quick $
