Search Advertising refers to advertising that appears on the results pages of your searches. Search Engines like Google and Bing organize ads on a results page to grab the searchers attention, while advertisers are able to target their ads based on the search terms context, the keywords they enter into the search engine indicate their interest in something, those keywords are bid on by advertisers hoping to capture the eye of the searcher with what they are looking for. Advertisers can also target geographically and by time of day.
This type of advertising is called Pay-Per-Click or PPC and their is a marketplace where advertisers can build campaigns for their ads and bid on the keyword phrases they believe prospective customers will use to search for their product or service, or of a related subject or item that may tempt the searching into considering the ads offer.
Display advertising is most familiar to people because they are used to highway billboards or ads in magazine with product pictures and descriptions. Display advertising takes a step off the search engine page and onto a mass network of affiliated websites that participate in the Ad marketplaces program. Display advertising has shown to be more cost effective for many types of businesses than the text based search ads.