One was an operating that had a monopoly that was nearly impossible switch away from and was bundling software to destroy specific competitors.
The other is a web page with tons of competitors, many of which work well, deciding what their own computers after you specifically requested them to do so.
No, the point is that Google is using their dominance in search, which isn't easy to switch away from, to compete in price comparisons. Google just having a price comparison tool isn't the problem, it's when they include it as a part of search. Which is using their dominant position.
While whether you can switch might be important from a user standpoint it's not necessarily a factor from a market standpoint. It's more about how much power you have and how you use that power. It might be very easy to switch to Bing, but Google still have power over >90% of the search market.
Doesn't seem that different from the case against Microsoft over Internet Explorer and Windows Media Player?