The most important thing in movement of the body is the hips. Almost all correct movement in humans originates from the hips. Ryu's hips in the example have the highest energy of all his body parts. In yours, there's no hip movement at all. This results in the torso not rotating either, the arm feeling disconnected and thus the punch weaker. In martial arts you are always taught that the striking limb (for example fist) is just the extension of your core.
Another important fact is the body parts that are locked. Example Ryu locks his front foot, yours doesn't, making the whole pose weaker. Another lock point seems to be the back arm, which does kinda lock in your animation, but without much intent (it's a bit too soft, you want to exaggerate the lock). Lastly, you lock on the back foot, which is just wrong. He's hitting with left arm, which is connected to the right foot, so if you lock that foot, again, you're breaking the movement.
Basically, just study your examples more. Try to look for gestures, like a limb behaving as a lock or loose, try to figure out the lines of movement, like the force of the punch flowing from left fist to right foot and being originated in the hip rotation.