What we refer to as a 'script' is a bundle of lines of code. A programmer would be making a bit of software and that piece of software is one, or consists of many scripts. So when you see someone selling an 'email extractor script' they will be offering a few documents of code in one languauge or another that can do as it says, extract email address from pages. A script is basically software, but often on a smaller or less professional scale. That's one way to look at it.