Difference between 維持｛いじ｝する and 保｛たも｝つ (to maintain)

Question

I've learnt two verbs which seem to mean the same thing, and I keep confusing them: 維持｛いじ｝する (to maintain; to preserve;  to improve) and 保｛たも｝つ (to preserve; to maintain; to support)

Can someone highlight the differences of usage for those 2 words ?

It would be great if other variants could also be described against those words, for example 養｛やしな｝う、持｛も｝ち続｛つづ｝ける、持｛じ｝する、立｛た｝ち行｛い｝く、etc.

Thank you

Answer 1

For 保つ the nuance I think is "to hold on to X, or to withhold the X". It is easy to see that if you fail in doing so, the situation will completely change.

• 正気を保つ (to mantain/keep one's sanity, possibly in the face of a situation which might make you literally insane)
• 平静心を保つ (to keep your calm)
• 平和を保つ refers to making effort to keep the peace.

Xを維持する means, with some efforts and maneuvering, you are maintaining the current situation, with emphasis on the maintaining.

維持する is also used with physical buildings, etc. referring to upkeep/maintaining the place.

• この神社を維持する (I) maintain this shrine.

Answer 2

I think what you have learned is absolutely correct: these are words with similar meanings, and you should not be confused. There are lots of words (in all languages) with very similar meanings, and often the only way to understand which is most appropriate in a particular case is from experience of hearing them used. So it's quite hopeless trying to learn the subtle distinctions by looking at lists of English words in dictionaries.

But there is an obvious difference between these two words, which is exactly analogous to the difference between "keep" and "maintain". "Keep" is a Real English (Germanic; that's why the past is 'kept') word, whereas "maintain" is a loan from French/Latin. Similarly 保つ is a Real Japanese (Yamato) word, whereas 維持(する) is a loan from Chinese. So there is a difference of register (or flavour), but it's not a simplistic question of 'formal' vs 'informal'.

Also 維持 is really a noun, so it's easy to make Sino-Japanese compounds with it, such as 維持費, the "cost of maintenance". (You should find a lot of commonality with other Yamato/SJ pairs.)