差不多 (almost / about the same)

Which one should I buy?

• You compare two phones in a shop. The prices, cameras and sizes are almost identical.
• this这zhè两个liǎng gècell phone手机shǒu jīabout equally差不多chà bu duō。 — "These two phones are about the same."

about equally差不多chà bu duō as an adjective: about the same

• A and跟gēn B about equally差不多chà bu duō / A and / with和hé B about equally差不多chà bu duō = A and B are about the same: I我wǒand跟gēnI我wǒolder brother哥哥gē geabout equally差不多chà bu duōtall高gāo.
• Alone after the subject, it can mean "nearly the same" or "nearly done": school assignment作业zuò yè写得xiě déabout equally差不多chà bu duō(completed / change)了le.

I我wǒand跟gēnmy我wǒolder brother哥哥gē geabout equally差不多chà bu duōtall高gāo。

about equally差不多chà bu duō as an adverb: almost, about

• Before a number or time: about equally差不多chà bu duō十点shí diǎn(completed / change)了le。 — "It's almost ten." about equally差不多chà bu duō五十个wǔ shí gèperson人rén — "about fifty people".
• Before all都dōu / all所有suǒ yǒu: to study at the same school同学tóng xué(plural)们menabout equally差不多chà bu duōall都dōucome来lái(completed / change)了le。 — "Almost all the classmates have come."

the classmates同学们tóng xué menalmost差不多chà bu duōall都dōucome来lái了le。

Two jobs, two positions

about equally差不多chà bu duōthen就jiùOK行xíng(completed / change)了le: good enough

• about equally差不多chà bu duōthen就jiùOK行xíng(completed / change)了le。 — "That's good enough." A relaxed attitude to small details.
• he / him他tāto be / is是shì(measure word)个gè"about equally差不多chà bu duōteacher先生xiān shēng"。 — said of someone who never bothers to be exact.

close enough差不多chà bu duōthen就jiùOK行xíng了le。

Recap

Read the full reference: HSK 4 grammar — Adverbs.