異動 and 移動: personnel changes and physical movement
Use personnel notices, department changes, room-to-room travel, and luggage transport to distinguish the two spellings of いどう. Read personnel changes separately from physical movement.
A department change and its notice
異動 (いどう) means a personnel transfer or change. 「父は春の異動で別の部署へ移った。」 reports the father moving to another department in the spring reshuffle. His departmental relationship changes; leaving the company is not stated.
「人事異動の知らせが社内に掲示された。」 reports a notice of personnel changes posted inside the company. The notice concerns personnel relationships, without establishing each person's actual transfer date.
Movement of people and objects
移動 (いどう) means movement or transport. 「会議室から食堂へ全員で移動した。」 reports everyone moving together from the meeting room to the dining hall. Their physical location changes between the stated places.
「荷物の移動には台車を使ってください。」 asks for a cart to be used when moving luggage. 移動 can concern objects as well as people, and the request does not report completed transport.
Choose the spelling through context
Both words are read いどう. Personnel notices and department relationships point to 異動; movement between rooms or luggage transported with a cart points to 移動.
A personnel change can accompany physical movement, but not every 異動 requires a change of location. A physical 移動 of people or luggage alone does not establish a personnel change.
Which spelling of いどう fits a personnel-change notice, and which fits luggage transport using a cart?
Show the answer and why
異動 fits the personnel relationship change; 移動 fits the physical movement of luggage. Use the personnel or location context to distinguish the identical pronunciations.