Most noticeably, Google said it would display results from at least three competitors each time it shows its own results for specialized searches related to things like shopping, restaurants and travel. In some cases, competitors will pay when people click on these results. The deal would last for five years and apply to any new search products Google introduces in Europe. Google also said it would make two changes similar to those requested by the F.T.C. It would allow rivals like Yelp to forbid Google from using their content in its specialized search services, yet avoid being penalized for that in Google’s normal search rankings. And it would eliminate some restrictions that have prevented advertisers from moving their ads to other companies’ services.

Since the investigation began in 2010, Google has expanded well beyond web search to new businesses including wearable computing and mobile software. All those other activities are beyond the reach of Wednesday’s settlement, illustrating how difficult it is to create effective rules of engagement for regulating Internet businesses.

“Google is no longer just a search company,” said Daniel Knapp, director of advertising research at the advisory firm IHS in London. “These concessions won’t have a material impact on Google.”

The changes, however, could be a boon for small companies that do specialized search, antitrust experts said.

“The importance of the decision is it gives some oxygen to companies that want to be in markets adjacent to Google, so they don’t live under this umbrella of being at any time suffocated by Google,” Mr. Wu said.

The European Commission has gone further than the F.T.C. in extracting concessions from Google in large part because European antitrust law gives more priority to protecting competing companies. United States antitrust doctrine gives dominant companies more freedom if they can prove they are creating a better product for consumers, which was a central factor in the F.T.C.’s decision to close its case without charges.