Difference between HTML and DOM

Well, if you look in things like firebug, you can also check out the "DOM". Then they usually mean the current state the HTML page is in. So if you, for example, have a html page and add a tag with javascript.

The actual HTML of the page is still the same, but the "DOM" however has changed.

Notice that this isn't the right definition of DOM, but I thought this might be what you meant.

DOM is a model of a document with an associated API for manipulating it.

HTML is a markup language that lets you represent a certain kind of DOM in text.

Other kinds of DOMs can be expressed in other markup languages, for example RSS and Atom can be converted to a DOM and manipulated with the same API as an HTML or XHTML document (more or less anyway; there are some HTML specific DOM extensions).

The Document Object Model (DOM) is a language-independent model made up of objects representing the structure of a document. HTML is one language for writing such documents.