Agraduate school (orgrad school) is aschool that gives advancedacademic degrees, such asMaster's degrees (M.S. orM.B.A.) andDoctoral degrees (Ph.D. orL.L.D. orD.D.S. etc.). A graduate student (or grad student) is astudent who has earned aBachelor's degree and is pursuing additional education in a specific field, though this is not always the case. InBritish English, the term "postgraduate student" is more common.
A graduate school is not always a separate school.
The term "graduate school" could be confusing because theverb "graduate" is also used to mean completinghigh school education or earning aBachelor's degree. The verb is used for all those types of schools, but the meaning of theadjective "graduate" is changed to mean "postgraduate" in the term "graduate school". The small change in meaning can be viewed with an air ofsophistication, where experienced students are often more aware of the issue, whilenovice students might not be aware, as being morenaive.