Rocky Mountain Instinct is a more comfortable and less aggressive enduro mountain bike designed for long rides and efficient climbing. The Altitude is designed for aggressive riding and enduro racing, whilst the Instinct is designed for long climbs and all-day rides.
Rocky Mountain Instinct has a steeper head tube angle and seat tube angle compared to the Altitude, though both share the same frames and many of the same components. On the Instinct, the bottom bracket and stack height are both lower than the Altitude’s, whilst the reach is simultaneously longer.