Does Google consider comparison pages to be a bridge page or are they referring to sites that redirect immediately into the advertiser site?
Direct linking is now banned on adwords so you can't directly link to advertiser's LP. The best way is to have your own LP with good content for quality score.
I'm not referring to direct linking. I'm asking what is Google definition of "bridge pages?" Would a one page comparison site be considered a bridge page?
Yes, most likely - best to add some more content so that it stands on its own. Or make it a subpage of an established site.
Here are some articles that might help clarify http://www.seoconsultants.com/articles/1007/doorway-gateway-pages.asp http://searchenginewatch.com/showPage.html?page=2167831 Honestly, 80% of PPC landing pages are bridge pages in my opinion...