#idk post came to me suddenly

适应 (適應) shìyìng and 习惯 (習慣) xíguàn can both be used to describe adapting to a new things, but they’re not the same!

适应 (適應) shìyìng

V. to adapt, to fit, to suit. This can be about something’s compatibility with a system, a sort of “coming into alignment with” maybe. 

适应需要
shìyìng xūyào
meet the requirments (say on a job app)

你的思想必须适应变化了的情况。
nǐ de sīxiǎng bìxū shìyìng biànhuàle de qíngkuàng
You need to adapt your thinking to the changed circumstance. 

习惯 (習慣) xíguàn

N. habit, custom. (不良习惯 - bad habit) nothing tricky here

V. to accustom to, to get used to. For me this kind of “adapting” feels much more about personal contexts. For example when I was studying abroad people would ask if I had 习惯ed to the city, to the food eg. 

他习惯早起。
tā xíguàn zǎoqǐ
He’s used to getting up early.

我已经习惯了纽约的生活节奏。
wǒ yǐjīng xíguànle niǔyuē de shēnghuó jiézòu
I’ve already gotten used to the pace of life in New York.

As always the more times you encounter them they will naturally disambiguate themselves, but hopefully this gets you going!