Here's an article that attempts (poorly) to differentiate between SEO and SEM.
They seem to be saying that SEO is more about designing a spider-friendly site and less about link building:
Generally, 90 percent of SEO relates to removing obstacles to the search engines finding and understanding the content's essence.Of course, you need a spider friendly site, but without a link building campaign there will never be good search engine rankings. Posted by James Trotta at February 9, 2005 6:30 PM
I find it interesting that someone wants to define SEO vs. SEM - given that there is still so much discussion of what SEO is. For example, there is the ongoing "black hat vs. white hat seo" whereby some SEOs actually say there is no such thing as black vs. white.
I'm part of that camp. I say black vs. white is entirely defined at the whimp of the SEs and is latched onto by SEOs who want to use a marketing distinction between themselves and others. After all, some of the "black hat" techniques today were legal a few years ago and embraced by "white hat" SEOs.
Given that - I think the article was too long in what should have been a very simple paragraph. SEO is focused entirely on optimizing a website to rank well in the SEs. SEM is incorporating paid-search, ads, and pretty much anything else related to the search engines that is NOT involved with natural ranking. That means even the site design aspect does not fall under SEO.
The problem is, most SEOs necessarily have to involve SOME SEM and that's when the line blurrs.
Posted by: Cryptblade at February 22, 2005 12:23 AMPaid directories and text link ads blur the line even more.
Posted by: James Trotta at February 23, 2005 12:45 PMTrade links with seo-search-engine-ranking.com
http://www.seo-search-engine-ranking.com/ad_network_222.php