Content match is very different. Sites sign up to have ads related to their site content show up throughout their sites. They receive a portion of the ad revenue. The search engine looks at the content of each page where ads are displayed in an attempt to determine the most highly relevant ads to show. If your ad is determined to be suitable, it will be displayed on this site. This is independent of any searching, though a search may have brought them there in the first place. An example might be someone on a homes foreclosure site finding your real estate ad. Another might be any site related to home improvements, etc.
The greatest value of PPC marketing is the ability to focus very tightly on your ideal prospect's needs and the search terms they would use if in the market to buy or sell real estate. Though the homeowner above will probably become one at some point in the future, it's highly unlikely that they'll be a reasonably reliable prospect at this time, even if they accidentally or out of curiosity click on your real estate ad from the home accessory site.
There are SEO (Search Engine Optimization) services out there that recommend leaving the Content Match on, and the clicks are definitely less expensive than the much more focused search term clicks. However, would you rather have 2000 clicks at 39 cents each yield two transactions a year, or 200 clicks at $1.50 each yield the same two transactions or more? There is a place for content match strategy, but it's a completely different campaign setup.
One of the greatest values of PPC marketing is the ability to zero in on your prospect before spending ad money. Though content match can be effective if implemented properly, I'll opt all day for someone who actually typed in the search phrase "mytown homes for sale." By turning off any content matching (default is "on" usually), you can set up your campaigns to result in displays of your ads only when the specific keyword phrases you designate are typed in.
