屋根 and 屋上: the roof covering and the rooftop area
Compare roof repairs with pots placed on a rooftop, without treating putting the pots back as changing the entire rooftop structure.
The covering above a building
屋根, read やね, means roof. 屋根を修理しました。 says that someone repaired the roof.
雨の音が屋根から聞こえます。 says that the sound of rain is heard from the roof. 屋根から gives the direction or source of the sound.
The outdoor area at the top of a building
屋上, read おくじょう, names the rooftop area. 屋上に植木鉢を置きました。 says that someone placed a flowerpot on the rooftop.
屋上から隣の建物が見えます。 says that the neighboring building is visible from the rooftop. 屋上 is the viewing place, and 隣の建物 the visible object.
Repairing a covering and handling objects in a space
屋根の修理と屋上の清掃 means roof repairs and rooftop cleaning. Distinguish repairing the covering from cleaning the upper area.
屋根を修理した後、屋上の鉢を元に戻しました。 says that someone repaired the roof and then put the rooftop pots back. The objects of 戻しました are the pots.
Was the entire rooftop put back in 屋上の鉢を元に戻しました。?
Show the answer and why
No. The rooftop pots were put back. 鉢を marks the objects acted on.