Almost identical? Far from it.
They are very different, in care requirements and in behavior. You have obviously not worked with Gaboons enough to witness a pissed off adult in full flow, they are NOT sluggish and slow. They may appear to be on the outside, but when they are in a bad mood they're one of the most formidable snakes on the planet. Ask any experienced venomous handler, if a Gaboon is 'Sluggish and slow'