By the way, I guess you wanted to say "大家好".

there are some difference between them.大学 is univerity, 学院 is college. In China, A university has more departments and majors than a college.A university must have more than three departments of disciplines prescribed by the state as major disciplines.And there are more than 5,000 full-time students.But in a college, there can be only one department of disciplines prescribed by the state as major disciplines and 3,000 full-time students.Generally speaking, a university is more comprehensive than a college. A college usually is more professional in some majors. A college can be upgraded to a university when it has developed more departments and it's educational institutions.But it doesn't mean that a university is better than a college.

学院is college and 大学 is universtiy. In China, there're many colleges in a university. In China, The National University is called 国立大学。

Usually, “学院" is translated as "college", and "大学" as "university". Generally speaking, "大学" is bigger and more comprehensive, while "学院" is more specialized. "学院" also means a college or school belonging to a university. "The National University" is "国立大学" in Chinese.

大学包含了学院，应该是国立大学