But what if you have multiple blogs, maybe in a custom domain, that you want your reader to search in combination? Or maybe you would like refinements to your search? That's when you use the Google Custom Search Engine.
There are advantages to both choices. The Blogger search is simple, with no options required (except the caption for the button), and provides the search results as a custom main page in the blog (very user friendly). The Google CSE is very versatile, with lots of settings, and it provides the search results in a Search Engine Results Page format.
The most relevant difference, in my opinion, the source for the searches. The Blogger search searches the blog directly, and dynamically. Whatever changes you made to the blog 5 minutes ago will be included in the search. The Google CSE searches against the Google Search Engine database, and will have results only as current as what GoogleBot found during its last pass through each web site included in the search.
A third alternative would be a Google Custom Search "Search Box" gadget, which you add directly from the "Add a gadget" wizard in Page Elements. Slightly less versatile than a Google Custom Search, the "Search Box" gadget combines blog searches and web searches, into a comprehensive and configurable multi tab search.
- Search this blog.
- Search websites linked in the blog posts.
- Search websites linked in the bloglists and linklists.
- Search the web.
It all depends upon what you think will serve your readers best. But consider the several choices, carefully.