both word are used exchangebly , i think Holiday is a contraction of holy and day, holidays originally represented special religious days. Holiday : a day when most people do not go to work or school, especially because of a religious or national celebration: usage of the word holiday : Religious holidays National holidays i think Vacation is when you decide to take a break to relax and travel Examples : They’re on vacation in Hawaii right now. You look tired—you should take a vacation. The job includes two weeks' paid vacation. a vacation home and when i was searching the differences between these two word i found , that : holiday is American English ( British too ) and vacation is British English. Other than that the two words mean the same thing. Which word to use just depends on who you are talking to.

not to be condescending to the two people who answered before, but neither are native English speakers. their explanations are close, but not exact. So a vacation is when you take time off from work or school. You may be going away from home or whatever, or you may be just spending time at your house instead of working. In American English, people always describe this as a vacation. In British English, one would say "I'm going on holiday(s)". In American English, a holiday is strictly a day fixed by law or custom on which ordinary business is suspended in commemoration of some event or in honor of some person. For example, Christmas. The British also use the word in this way. however, Americans are much more likely to use the word 'vacation.'

When I'm not on holiday I'm on vacation. Holiday comes from "holy day", and referred to the religious holy days where people did not work but went to church. Vacation comes from "vacate" and means a space between working days. So technically the same.

When you work, you take a vacation example 2weeks to have a rest. Holiday is a day when you celebrate. Now im not sure about summer holidays or vacation at school

To celebrate the holidays only and Vacation Leave of absence from work in order to relax