Up and down; top and bottom — indicates vertical positions or the upper and lower ends.
箱の上下を確認してからラベルを貼ってください。
Please check the top and bottom of the box before sticking the label.
気温の上下が激しくて服装に困る。
The large swings in temperature make it hard to choose clothing.
列車の上下線ともに遅延が出ている。
Both the up and down train lines are delayed.
Upside-down — a state of being inverted. Often used as 上下になる (to be turned upside-down).
地震で家の棚が上下になって中の物が散乱した。
The earthquake turned the house shelves upside-down and scattered the contents.
箱を逆さまにすると、中の仕切りが上下になる設計だ。
If you turn the box over, its internal partitions are designed to switch top and bottom.