Vietnamese vs Chinese
Is Vietnamese similar to Chinese? How close are they?
Vietnamese and Chinese are unrelated (Austroasiatic vs Sino-Tibetan), but centuries of Chinese influence left Vietnamese with a large Sino-Vietnamese vocabulary and similar analytic, tonal structure. Vietnamese is now written in a Latin alphabet.
The short answer
They are unrelated (Vietnamese is Austroasiatic, Chinese Sino-Tibetan), but centuries of contact left a large Sino-Vietnamese vocabulary, so 注意 zhùyì is chú ý. Both are tonal and analytic, with no verb conjugation. Vietnamese is written in the Latin-based chữ Quốc ngữ.
The verdict
Sino-Vietnamese words map onto Chinese (điện thoại / 電話, đại học / 大學). Both are tonal and analytic. Word order differs in noun phrases: Vietnamese puts modifiers after the noun.
Closeness score
8 / 30
Mutually intelligible?
no
Shared vocabulary
Estimates of the Sino-Vietnamese share range widely (often cited around 30% to 60% of the lexicon, higher in formal registers)
Which first?
Chinese first makes Sino-Vietnamese vocabulary click.
Kungfucius says: Vietnamese kept the vocabulary and swapped the characters for diacritics.
Side by side
電話 / 电话
diànhuàSino-Vietnamese reading of 電話; the characters are no longer written in Vietnamese.
大學 / 大学
dàxuéSino-Vietnamese reading of 大學. Note the modifier order matches Chinese here because it is a fixed Sino-Vietnamese compound.
國家 (国家)
guójiāVietnamese keeps the final -c (from Middle Chinese -k) in quốc.