Restrain and refrain has same meaning “stop yourself or a person doing something “.
However, if you are using “restrain”, you are stopping yourself or the person with force
which could be mentally or physically both. For example- “ police had to restrain the crowd
using tear gas.” or “ I couldn't restrain myself to talk back to her.” On the contrary,
refrain doesn't show any force. It indicates doing something which one isn't supposed to do.
For instance- “the students should refrain from gossiping during the class." or
“you have gained weight so you must refrain from eating oily food”.
