A correction: 'What is the difference between abstain , refrain and restrain'. Abstain and refrain are very similar. Abstain is usually used for 'bigger' things. You can abstain from Sex, Alcohol and voting! Refrain is usually used for smaller, less important things, and for shorter times. You can refrain from singing in class, you can refrain from spitting in public. Restrain is usually when you stop someone or something else from doing something. You can restrain your dog, or restrain an angry friend. Although you can also restrain yourself. So - by abstaining from something, your are restraining yourself, or restraining your urge to do that thing. So: He abstained from sex for three days after his operation. He refrained from picking at the scar. She restrained her dog, after it tried to bite the cat.

First, you question is not correct, it should be 'what is different about abstain, refrain and restrain I presume you want to know their difference as a verb Abstain and refrain are the same thing, you can use it exchangeablly. They mean" deliberately do not do it" Abstain can also use in vote, if someone abstained in a vote, he decided not to vote. restrain usually followed by an emotion or or one restrains itself from doing something,which means " prevent yourself from showing that emotion or doing what you wanted or intended to do".