What is the difference between absolute and relative URLs?
The big difference is that absolute URLs will always include the domain name of the website with http://www. Relative links show the pat to the file or refer to the file itself, which is useful because it can transfer a user from point to point within the same domain.
In the following episode of AskGoogleBot, John Muller talks about this difference, and goes into if there is a preference in how a search engine crawls and indexes them. Something like this could be quite useful if you’re running your HVAC website, or for any kind of website, for that matter.