The difference is: vacation is a some kind of a private spare-time period, you can get on your job. Holidays are especial days which were reserved to commemorate something important for everyone or for a group of people, community e.t.c. For example, holidays are a dozen days for resting to celebrate a New Year coming in Russia, or holidays like the resting-days in school. Vocation as a time for resting, worker got on his job for himself only. It's his private spare-time only, not a common celebration.

一个是假日，一个是节日。

Hi... It is the same meaning but "vacation" is more use in USA and "holiday" is more use in England.