Reading about both separatedly, looks like the same, html+xml+javascript.
What's the difference between then? Is there any?
XHTML is a w3c standard, a form of HTML that also strictly conforms to XML.
DHTML is a largely deprecated term (it is short for 'Dynamic HTML') which was introduced when the first early static web sites started introducing client side scripting to make the page more 'dynamic'. Nobody really talks in terms of DHTML any more (the term got superseded by 'ajax', and 'web 2.0', and 'web app')