两张皮

Traditional (Taiwan): 兩張皮

liǎngzhāngpí ㄌㄧㄤˇ ㄓㄤ ㄆㄧˊ

    • two things that should work together but are disconnected
    • a disconnect (e.g. between theory and practice)

Character by character

Saying俗语俗語

Idiom惯用语 · Widely known

Literally
two skins
Meaning
Two things that should work closely together but are disconnected, like two separate layers of skin. Critical, often about theory and practice or two departments.

Sources