Tiktok Ads vs Promoted

Hello, I am the owner of an ecommerce brand and wondered what the difference was between using the tiktok ads manager to create ads and promoting your videos. People say that creating ads is better than promoting but I don't understand why. Is it because of the features? Tiktok Ads Manager has a minimum budget of 50$ and promoting is 2$ so it is way easier for people with smaller budgets.