It is seen that Facebook has recently began testing search ads. With this, it is seen to position itself in direct competition with Google's advertising offering.
As far as the testing goes, the companies will not be paying for the advertisements. The format of the ads will be similar to mobile news feed ads with the same headline, image and text format. It will however will be labelled with the "sponsored tag".
Facebook is usually used to search regarding friends, events, pages and apps. As compared to Google, people are likely to use Facebook Search in a different way.
For the time being, the testing is being rolled out in the US and Canada only.