The DE version is applicable for German companies subject to German VAT law.
Here, the VAT identification numbers are checked according to the German legal requirements. The interface of the BZSt. is used for the check.
Prerequisite for the use of the DE version is an own valid German VAT ID number.
The EU version is not subject to country-specific legislation but uses the EU Commission's interface for verification.
Ultimately, this is suitable as an application for EU companies based outside Germany.
The prerequisite is a valid own EU VAT ID no.