The title is pretty self-explanatory. What is the difference between these three? From what I can tell these are almost the same.
In a nutshell,
Is the Austrian official term
The German official term
The EU German official term for the same thing (who said that it should be simple?), the EU English term is
And all denominate a unique identifier for someone (a fiscal entity) who is officially entitled to charge and be charged by the national administration with VAT.