It's very simple: Unit tests test a specific "unit" (i.e. in an OO language, that's a class) and integration tests test the ingration of multiple units.
In OO languages, I personally prefer unit tests with all dependancies stubbed or mocked out to verify the interface of that specific unit or component.
In OO languages, I personally prefer unit tests with all dependancies stubbed or mocked out to verify the interface of that specific unit or component.