Такая же разница, как и между больницей и поликлиникой :)

thank you a lot! these answers are great!

João pretty much got it right here. In a different context I've also heard clinic to refer to small doctors offices, like rural doctors or children's doctors most often.

I agree with what João said. Also, in a hospital, you could stay overnight or for several days, or longer. In a clinic usually you are there for only part of a day.

Hospital is a place where you treat a lot of diseases. You can find specialized doctors of all areas. Generally, hospitals are bigger than clinics. Hospital you also have a emergency department to receive patients that need fast support. Clinic is a place where you can visit a specialized doctor to receive treatment, but it doesn’t has emergency department. I hope that this little explanation helps you. Bye.