When we search Google for the term “SEO” most of them who uses "Search Engine Optimization" in the title tag and description gets it bolded (as SEO is an acronym) but not for all results…..(Check SEOmoz, and tools.seobook, the term "Search Engine Optimization" is not bolded). What could be the reason for this? I could not figure out the reason for this! Why don’t we find a uniformity here by Google! Can anyone explain?
google treated metas in different ways, like its upto keyword worth being searched for. Sometimes google treated keywords of their relevancy with the search term, like when you search for SEO, there is a relevancy in metas for the same keywords, so it became bolded rather search engine optimization keyword. Its all about keyword relevancy with the given search term. Hope this could give you some idea, and if you are still not clear you can come up with more questions.