We know that Victor is an enforcer. He can occasionally drift into the box and score. That's his game. He can also be a little heavy and cumbersome, and he can lose concentration.
Lemina is a bloody livewire. He's always quick to the tackle, tigerish even, but fair and comes away with the ball. He can be an enforcer pairing with Romeu and he can get into the box ready to score. And technically, he's a level above Victor, one can easily see that already. He also happens to be pretty good in proper defensive positions. Apparently he has played all along the defensive line and done well, so I agree he is a different player. And on the evidence so far, he's better and more versatile.