Simple: You are trying to compare apples to oranges. Your in-state school is a public university - goal is to admit as many qualified “instate” candidates as possible for a lower tuition than kids coming from out of state - since much of the funding comes from the state government.
NYU is not New York’s “state school,” (SUNY is). NYU is a private university - not public - and more selective (and more expensive). You are very lucky to have been admitted to your instate school which just happens to be a top national university!