差不多 / 几乎
chàbuduō / jīhū
Similarities
Both 差不多 and 几乎 work as adverbs meaning “almost”, “nearly”, “very close to”.
他汉语说得很好，差不多跟中国人一样。
He speaks Chinese very well — almost like a native speaker.
他汉语说得很好，几乎跟中国人一样。
He speaks Chinese very well — almost like a native speaker.
Either word works in this sentence.
1. With adjectives
差不多 can go directly before a monosyllabic adjective; 几乎 usually needs words such as 一样, 这么, 那么 or 了.
他们俩差不多高。
They're about the same height.
他们俩几乎一样高。
They're almost the same height.
他比我几乎高了一头。
He's almost a head taller than me.
2. With numbers
李老师差不多六十岁了。
Teacher Li is about sixty.
几乎六十岁 is not used — 几乎 does not go before a number.
3. As an adjective
姐妹俩性格差不多。
The two sisters have similar personalities.
几乎 cannot be used this way — it is never an adjective.
4. “Almost happened”
几乎 can express that something almost happened but in the end did not.
这件事我几乎忘了告诉你了。
I almost forgot to tell you about this.
差不多 cannot be used with this meaning.
Quick comparison
| 差不多 | 几乎 |
|---|---|
| approximately, almost the same | almost; almost happened |
| can go before a number | cannot go before a number |
| can be an adjective | cannot be an adjective |
| cannot mean “almost happened” | can mean “almost happened” |
差不多 → almost, approximately, similar
几乎 → almost; almost happened, but didn't