Google's html5 banner specification is different to adform's.
google's: https://support.google.com/richmedia/answer/2672517?hl=en&ref_topic=2672541
Basically the way the URL works and the javascript files they say to include differs.
is it possible to create a banner - specifically the clickTAG / url function, that works for both networks?
Adform is Google adwords third party vendor. Google adwords can not directly embed your banner Here is the vendor list : https://support.google.com/3pascertification/table/4572577