no-follow and do-follow both are html tags, which are use for show your link status. If you target Google then both are matter. In Google, if you build backlinks help to increase Link juice of your website, which is most important factor for increase the ranking and Page rank of your website, called do-follow links. If they don't take participate then they called no-follow backlinks and in Google, no-follow links are waste of time.
If you target other search engines then both are same and both type of backlinks help to increase the ranking of your website.