上下床
shàng​xià​chuáng

bunk bed

上下床 shàng​xià​chuáng
bunk bed
bunk bed; a pair of beds stacked one above the other
vast difference
(literary) an expression referring to a massive gap in status or character between two people; based on an anecdote from the "Records of the Three Kingdoms" where a host slept on a high bed and made his guest sleep on a low one