How to say this expression in chengyu?

[Lafaso870]

I was wondering if anyone could tell me how to say the following as a chengyu?

You change the external wrapping, but the contents are still stay the same, ie. superficial/meaningless change? Or something to that effect (there are a lot of ways you can express that sort of meaning in English).

I'd appreciate any help! Thanks

[candie111]

it means '去其糟粕 ，留其精华' (qu qi zao po liu qi jing hua ）in chinese