They say that great punchers are born, and not made. It’s true. Say you have a large number of individuals all with the same technique and body weight. Despite this, there will be variances in punching power. People have different body shapes and ways they move their body, which will affect how well they transfer and generate power.
Other than this, weight also makes a huge difference. A big person who can decently throw around their weight is always dangerous, even if they are women who are generally regarded as weak. The hands of big people, are quite literally heavy hands.