The address bar in Firefox will run a search if you enter something that doesn't look like a URL. But it won't send whatever you're typing to the search engine

The address bar in Firefox will run a search if you enter something that doesn't look like a URL. But it won't send whatever you're typing to the search engine looking for search suggestions, for example. You need to use the search field to get search suggestions. In contrast, in Chrome, you can either have search suggestions and your search engine seeing every URL you type, or no search suggestions at all, depending on how you set your prefs.