Is vietnamese and Thai the same language?

No, Vietnamese and Thai are not the same language. They are completely different languages with different origins, grammatical structures, and vocabularies.

Here's a breakdown:

* Vietnamese belongs to the Austroasiatic language family, specifically the Vietnamese-Muong branch.

* Thai belongs to the Tai-Kadai language family, specifically the Tai branch.

While they are both spoken in Southeast Asia, they have very little in common linguistically. You would not be able to understand one language if you only knew the other.