| Difference | Microsoft | Mozilla |
| Member Names | Case insensitive? | Begins with lower case letter |
| XMLHttpRequest Creation | New ActiveXObject ("Msxml2.XMLHTTP") | New XMLHttpRequest() |
| XMLHttpRequest.open("some host") | OK | file:// documents can access http:// documents but you need to enable Universal BrowserRead privilege in your scripts. Additionally, "foo.com:80" and "foo.com:313" are considered different hosts for security purposes. You cannot open a connection to a different host. |
| DOMParser CreationDOMParser() | Not available | New |
| XMLSerializer CreationXMLSerializer() | Not available | New |