I just read in a book 暑中休暇 and wondered the difference with the three others, but there is nothing on Google that really explains what the nuance is.
I think 夏休み is like the most general, 暑中休暇 maybe is the most literary (?), and I've only seen the others in 新聞s.
Anyway, I'm hoping someone could give me a real explanation on how to use the four words properly, and if there are english equivalents.
Thanks!