As … as: bằng / như

To say two things are equal, put the adjective first, then bằng, then what you compare with: Con cao bằng ba rồi. You're as tall as me now (a father to his son; in Hà Nội, bố). Bằng means "equal". It is the everyday word for "as … as" with almost any adjective, and especially common for things you can measure: height, size, age, price. (Bằng also means "by" or "made of": đi bằng xe máy, go by motorbike.)

Như means "like". It fits when you describe how something seems rather than measure it: đẹp như hoa (as pretty as a flower). With cũng before the adjective, it means "just as … as": Hôm nay cũng nóng như hôm qua. It's just as hot today as yesterday.

To say two things are the same, end with bằng nhau (equal to each other): Hai phòng này rộng bằng nhau. To ask, use có … không: Tiếng Việt có khó bằng tiếng Trung không?

For "not as … as", put không before the adjective and keep bằng: Không khó bằng. It's not as hard. For "more … than", use hơn instead: cao hơn, taller.