I'd love to get a bike but I have no idea where to start.

They all look the same to me. What's the difference between a $100 bike and $500 bike?
I live in the city so I'll mostly be used it on paved surfaces. I'd love a simple bike like this (
Walmart.com: 26" Men's Huffy Cranbrook Cruiser Bike, Champagne: Bikes, Scooters & Skates). This particular one gets 4 stars but kind of bad ratings.