ながらWhile ~ing, During, As

とき expresses the time of an action or event, like the English 'when'. It can be used with nouns as in 雨の時 'when it rains', verbs as in 父が帰ってきた時 'when Dad came home', or adjectives as in 暑い時 'when it's hot'. In contrast, ながら is used when doing something while performing another action. It is used only with verbs, and unlike とき, the subject of both phrases must be the same, e.g. 音楽を聴きながら走る 'listen to music while running'.

Both forms involve the idea of simultaneous or ongoing actions, but differ in structure and nuance. ているあいだに expresses that something happened during another ongoing action, e.g. 勉強しているあいだに電話がかかってきた ('The phone rang while I was studying.'). ながら shows one subject doing two things at once, e.g. 音楽を聴きながら勉強するのが好き ('I like to study while listening to music.').

ながら attaches to verb stems to express performing one action simultaneously with another, e.g. 音楽を聴きながら走る 'listen to music while running'. In contrast, ついでに follows various words or phrases to convey the idea of taking advantage of the opportunity to do another thing at the same time, e.g. 買い物に行くついでに走ってきた ('On the occasion of going shopping, I went for a run.').

ながら attaches to verb stems to express performing one action simultaneously with another, e.g. 音楽を聴きながら勉強する 'listen to music while studying'. In contrast, 中 attaches to nouns to express 'while doing X,' and there is no requirement that what follows must be an action performed by the same subject, e.g. 会議中に電話がかかってきた ('A phone call came in while I was in a meeting.').

ながら attaches to verb stems to express performing one action simultaneously with another, e.g. 音楽を聴きながら走る 'listen to music while running'. In contrast, 間に can follow various words or phrases to express doing something while a certain state or condition persists, e.g. 若いうちにマラソンを走りたい ('I want to run a marathon while I'm young.').

かたわら and ながら are similar in that both can describe performing two tasks at once, but differ in nuance and usage. かたわら follows noun + の or the dictionary form of verbs, and typically implies performing a secondary action alongside a main one. It is often used with habitual actions, such as doing a side job or hobby along with a main job. In contrast, ながら is a more versatile way of expressing two simultaneous actions.

がてら and ながら both convey performing two actions together, but differ in nuance. がてら expresses a secondary or incidental activity done in addition to a main one, e.g. 犬の散歩がてら、コンビニに寄った ('I stopped at the convenience store while taking my dog for a walk.'). In contrast, ながら typically describes two actions of relative importance performed simultaneously, e.g. テレビを観ながらご飯を食べた ('I watched TV while eating dinner.').

ながら attaches to verb stems to express performing one action simultaneously with another, e.g. 音楽を聴きながら走る 'listen to music while running'. In contrast, うちに can follow various words or phrases to express doing something while a certain state or condition persists, e.g. 若いうちにマラソンを走りたい ('I want to run a marathon while I'm young.').

ているところだ and ながら both can express ongoing actions or states, but are used differently. ているところだ focuses on being 'in the middle of' something and implies that the speaker is occupied with that action, e.g. ご飯を食べているところだ ('I'm in the middle of eating.'). In contrast, ながら expresses simultaneous actions, e.g. テレビを観ながらご飯を食べる 'watch TV while eating'.

ながら and つつ overlap in some uses but not in others. When used to express simultaneous actions, e.g. コーヒーを[飲みながら・飲みつつ]本を読む 'read a book while drinking coffee', they are essentially identical in meaning, with the only difference being that つつ is more formal and literary. There are certain phrases, however, e.g. 生まれながら 'from birth', where only ながら works and つつ cannot be used.

つつ (when used by itself) and ながら both attach to verbs to express 'while doing', but つつある differs in usage. Specifically, ながら describes two actions performed simultaneously by the same subject, e.g. 音楽を聴きながら走る 'listen to music while running'. In contrast, つつある refers to a continuing process and is not typically used with physical actions, e.g. 物価が上がりつつある ('Prices are continuing to rise.').