NEW YORK — Is Microsoft's Bing really a better search engine? Since it debuted last month, it has earned praise for the smart way it presents results and how it lets users preview Web sites without clicking through to them.

Yet a closer look at its results reveals why loyal Yahoo users may not end up happy with the deal the company announced Wednesday, which calls for Bing to replace Yahoo Search.

ComScore Inc. says 19.6 percent of Web users go to Yahoo for their searches. Microsoft draws fewer, at 8.4 percent. That's up just slighly from the 8 percent it captured before Bing launched at the start of June. It didn't make a dent in Google's commanding 65 percent market share.

I think I can see why. Not only is using Google such an ingrained habit that we talk of "googling" something, but also its technology is better in some key ways. I found Bing to be less comprehensive than Google and, surprisingly, Yahoo Search. It simply returns fewer results for a lot of search terms.

With common terms like "cars," all the search engines return oodles of results. Yahoo reports 2.56 billion pages with that term. It doesn't matter so much how many pages they report, as long as they give relevant results, and all do.

Then I tried to hunt for something purposely obscure, like background on the country manor that my sister is interested in buying. Google gave me 46 links, Yahoo 15. Bing supplied just six.

Of course, even in this kind of query you might not have time to look through every link. So if Bing has six and they're good, that's fine.

Yet in the country manor search and other cases, often at the fringes of what you'd expect the Internet to know, I found the most relevant results in Google and Yahoo only.

Years ago, search engines competed by citing their "index size" — basically, how many pages they had collected in their database. Google played this game too. But as Google grew to dominate the scene by presenting better results, Web users lost interest in the statistics. Google doesn't make a big point of them anymore either, though it did say last year that it had more than 1 trillion Web pages catalogued.

Looking at results from Bing, it may be time to care about search index size again. That's especially the case because in other respects, the top three engines are so similar as to be nearly indistinguishable.

All of them present neat and clean search pages and advertising that's placed through an auction process (advertisers bid for the right to show their ads alongside certain search terms, and pay the search engines when a user clicks on an ad). Search for a common term like "diapers," and they yield nearly identical results.

They do have other little things that set them apart. Google injects a helpful little map when it finds a location among the top results. Yahoo has (or soon we might say "had") a Search Pad application that lets you annotate your results, a useful aid in an extended research or shopping project.

Bing has earned praise for the smart way it presents certain search results. For instance it breaks down some results by category, giving you an easy way to quickly hone a search for "swine flu" with information on "symptoms" or "causes." It will also helpfully show previous searches you've made in a column to the left of the results.