Question: What is the difference between 抽烟 (chōu yān) and 吸烟 (xī yān) which both pertain to smoking?
I‘ve ordinarily asked people
你抽烟吗 (nǐ chōu yān ma = "do you smoke?")
for which nobody has acted oddly about (at least, in regards to my Chinese), so I assumed it was correct, but maybe
你吸烟吗 (nǐ xī yān ma = "do you smoke?")
However, I ordinarily see
禁止吸烟 （jìn zhǐ xī yān = "smoking is forbidden")
on No Smoking signs, e.g.
which, up until recently, I thought said
禁止抽烟 (jìn zhǐ chōu yān = "smoking is forbidden" [presumably])
but this is incorrect, and it doesn't seem to be commonly used (possibly even an invalid phrase).