説明 and 案内: explaining details and showing the way
Compare explanations that support understanding with guidance about locations and access.
Making details understandable
説明 is read せつめい and means making details, reasons, or methods understandable. 「使い方を説明します」 says that the speaker will explain how to use something.
「もう一度説明していただけますか」 politely asks for another explanation. It requests information needed for understanding, not another trip to the same location.
Guiding someone to a destination or service
案内 is read あんない and refers to showing the way or providing information about using a facility or attending an event. 「駅まで案内します」 means that the speaker will guide someone to the station.
「会場の案内を読みました」 means that the speaker read the venue information. 案内 does not always involve a person accompanying someone; it can also be information in a document or on a sign.
An explanation within a tour
「館内を案内しながら、展示について説明しました」 says that the speaker explained the exhibits while showing someone around the building. Guidance with movement and explanation of content occur together.
The words can overlap in texts such as application instructions. Choose according to whether the focus is helping someone navigate a route or process, or understand its details and reasons.
How would you offer to take someone from the entrance to the meeting room?
Show the answer and why
You can say 「会議室まで案内します」. To explain the meeting's content instead, use 説明, as in 「会議の内容を説明します」.