ながら VS あいだ(に)

·        ながらwhile; during; as; to do two things simultaneously; (emphasizing the more 2 or more  actions going at the same time)

 

·        あいだ means while; during a certain period of time,～something happened.（All the time that A took place B was also happening.）

雨(あめ)が降って(ふって)いる間(あいだ)に本(ほん)を読んだ(よんだ)(I read my book while it was raining)

 

·        あいだに　The nuance is that B is an event that occurred (started & finished) at some point during the period A took place.

EX.雨(あめ)が降って(ふって)いる間(あいだ)にポスト(ぽすと)が配達(はいたつ)されました(While it was raining the post was delivered.)。）

 

 

 

Note:　If you want to use [あいだ] as a simultaneous action, you should use Te-form+いる

Examples:

私は　　 あるいている　あいだ/あるきながら（While walking)/　コーヒーを　のむ。

I drink coffee while walking