Google bans categories of ads, and bans advertisers that it views as bad actors, the same way it does with search. It also uses an algorithm to figure out what ads to show you, the same way it does with search results. It uses a lot of the same data (location, history, preferences, etc) to make those decisions.

The only difference I can see is that advertisers pay money to influence that algorithm (ie, a company willing to pay more money will win an auction against a company that has less money). Is that what you're referring to as the thing that makes it more free and less opinionated?