They are only similar in the sense that they are triple damage attacks. But Trinity Smash is a straightforward attack, while Real Impact is an uppercut that goes up.
Also, the guy in the video is using Distortion, which is a glitch that consists of dramatically increasing damage if you activate DT at a very precise moment during a move. Distorted Real Impact is one of the most powerful (if not the most powerful) move in the game, it literally destroys enemies. But DT needs to be timed perfectly, or you will just deal normal damage and waste DT gauge.