Hi Nanako, In addition to your brilliant submission and the contributions preceding mine; I would suggest that, while the nuance between the two is so subtle, to refrain can be seen as a moderate action taken with gentle intentions. The action doesn't cost the "action taker" much. In other words, to simply pull back from something, and to simply restrain oneself from doing or continuing something. Abstain on the other hand, would be to deliberately stand 1000 miles away from a particular element. Mostly because not doing so might have dire consequences. So, it involves stronger decisions and intentions, all rooted in strong aversion towards the element in question. Cheers!

Grammatically you can refrain only from a gerund, not a noun, you can abstain from both (i.e. both from smoking and from cigarettes). Refraining is simply not doing something, abstaining is not doing something.which is a privilege or a pleasure.

Nanako, you have some good observations. In the above context, there is not really any difference. They might be interchangeable, depending on the context for not voting. However, generally-speaking, 'refrain' has more of a sense of holding back from doing something. It has the sense of self-control. Abstain, particularly with regards voting, can have the sense of objecting to something by not voting. It does depend on the context. So, although the words may seem interchangeable on the surface, and it is true that you might use either word, you must look for the context before deciding if they interchangeable or not. If there is not much context, then use either - at least with regards to voting.

This is a really good question! A lot of the time, these words are used interchangeably, but I think you're right about your usages. In my experience, 'refrain' is used for a 'one time' or 'temporary' situation, whereas 'abstain' holds the connotation of a longer timeline and be of conscious effort. 'Abstain' is a little more personal, and seems more like keeping oneself from something. For instance "I plan to abstain from chocolate (but it's something I would normally eat). For these reasons, I would amend your example sentences to this: 1. I plan to abstain from voting. (<- indicates that you won't vote, and will try to not vote for a longer period of time.) 2. I plan to refrain from voting this time. (<- suggests that you won't vote this time, but you might next time.) I hope this helps to clarify them a little! :)