XML attribute vs XML element

Question

At work we are being asked to create XML files to pass data to another offline application that will then create a second XML file to pass back in order to update some of ou

Answer 1

"XML" stands for "eXtensible Markup Language". A markup language implies that the data is text, marked up with metadata about structure or formatting.

XHTML is an example of XML used the way it was intended:

El Jefe insists that you
    MUST complete your project by Friday.

Here, the distinction between elements and attributes is clear. Text elements are displayed in the browser, and attributes are instructions about how to display them (although there are a few tags that don't work that way).

Confusion arises when XML is used not as a markup language, but as a data serialization language, in which the distinction between "data" and "metadata" is more vague. So the choice between elements and attributes is more-or-less arbitrary except for things that can't be represented with attributes (see feenster's answer).