The Difference Between うちに, あいだに and ところ

The difference between うちに, あいだに and ところ in Japanese

1. ～うちに (while)

Meaning:
～うちに can be used with 2 meanings

A: Doing an action before another state changes.

B: During the time an action or event takes place, some state changes.

Usage:
A: Doing an action before another state changes.

～N の/ Vる / V ている / Vない/Aい/ Na +うちに …

The part in ～ shows the state before the change. The part … is a volitional action.

Examples:
日本(にほん)にいる　うちに　一度(いちど)富士山(ふじさん)に登って(のぼって)　みたい
While I'm still in Japan, I want to try climbing Mount Fuji once.

明るい(あかるい)うちに庭の掃除(にわのそうじ)をしてしまおう。
Let's clean the garden while it's still light.

B: Used to mean that during the time an action or event takes place, some state changes.

Vる / V ている / Vない+うちに …

The part in ～ shows an ongoing, continuing state. The part … shows a change of state that is not intended by the speaker.

Examples:
音楽(おんがく)を聞いて(きいて)いるうちに眠って(ねむって)しまった
While listening to music, I fell asleep.

気づいかない(きづいかない)うちに外(そと)はくらくなっていた。
Before I noticed, it had got dark.

2. 間 (あいだ) … / ～間に(あいだに)… (during)

Meaning:
～間… : When an action takes place over a long period, another action also takes place continuously during that period.

～間に: When an action takes place over a long period, another action happens at just one point within that period.

Usage:
N の/ Vる / V ている / Vない + 間… / 間に
Here both the ～ part and the … part are continuous actions

Examples:
お母さん(おかあさん)が昼寝(ひるね)をしている間、 子ども(こども)たちはテレビを見ていた
While mother was taking a nap, the children watched TV

私(わたし)が旅行(りょこう)で留守(るす)の間、うちの犬の世話(せわ)をお願い(おねがい)できないでしょうか
While I'm away travelling, could I ask you to look after my dog?

私(わたし)が旅行(りょこう)で留守(るす)の間に、庭(にわ)に草(くさ)がたくさん生えて(はえて)しまった
While I was away travelling, a lot of weeds grew in the garden.

3. 〜ところだ / 〜ところ(+ particle) (at the point of)

Meaning:
When ところ is used in the sense of a point in time, depending on how the preceding verb is conjugated, ところ means the moment just before, the moment just after, or the very middle of that moment.

Usage:
Vる / V ている / Vた + ところだ / ところ(+ particle)

When ところ is in the middle of a sentence, depending on the following verb it may be followed by particles such as を,で,へ

Examples:
試験中（しけんちゅう）、となりの人の答え（こたえ）を見ているところを先生（せんせい）に注意（ちゅうい）された
During the test, the teacher warned me just as I was looking at my neighbour's answers.

ケーキができ上がった（できあがった）ところへ子ども（こども）たちが帰って（かえって）きた
The children came home just as the cake was finished.

See also:
N3 Grammar That Has Appeared in the JLPT
15 N3 Grammar Patterns Commonly Used in Conversation