Different countries, different money. The numbers on the notes look very different — but a bowl of phở costs about the same in every country, just with a different number on the price.
One euro ≈ 27,000 đồng. So the same ice cream might cost €3 in Spain or 80,000 đồng in Saigon. Same ice cream — different number.
That's why Vietnamese money has so many zeros. A 500,000 đồng note isn't more valuable than a €20 note — it's about the same.