The difference is Trump was walking on a decline which had a wet surface, wearing dress shoes. It was slippery. Biden is an old guy who can barely walk anyway (for his own safety, he should be using a walker) and going up steps that offer no more of a challenge than any steps do... well, except that everyone was watching. It never fails; as soon as Biden is doing something his handlers can't control, he falls... errr, fails. Yeah, that's it. I meant fails.
And not that you asked for, nor should listen to my advice, but you really need to flush out your headgear. If you let Trump live there forever, rent free, you'll just continue a long slow decline into madness.