When you're earning from AdSense, you are unlikely to be paid by the US entity unless you are registered in the US or in general offshore jurisdictions, like the Carribean.
If you are in the EU, you will be invoicing Google Ireland, and covering VAT via reverse charge.
If you are in MENA/APAC, you will be invoicing Google Singapore.
See:
https://support.google.com/adsense/answer/1322028?hl=en
Also, AFAIK, it's royalty income solely if you are making use of YouTube AdSense, as you are being rewarded for video watches. If you use the general AdSense for Web or AdMob for Apps, it will be classed as business income.