Power

The biggest difference between working as a food service manager for someone else and the manager of your own restaurant is power—the power to pick the name, hire the staff, set the rules, and force every customer who visits to at least consider ordering the haggis pizza you're sure would be a hit if people just gave it a chance. As the manager-in-chief, it's all on you.

 
You got it...at least until the police get involved. We're actually fairly sure you can't wing salt-water forage fish at passing toddlers. (Source)

When people visit your place, they'll be fully at the mercy of your gastronomical whimsy, eating your food, made from your ingredients, in the way that you decided to combine them. Want a no food pictures policy? Done. How about a massive anchovy mascot who runs around flinging tiny fish at children on the sidewalk outside your parlor? You got it.

Your power, however, has its limits, as power often does. Remember, people can decide not to eat at your restaurant and employees can decide not to work for you. You can make all the decisions you want, but making them badly will often mean losing everything you've worked for.