Science is a branch of knowledge which never declares that the theory it has propounded, is the utmost truth. On the other hand religions propound that everything which is in their book is unalterable and can never be changed. This is the great difference between both the field. One theory of science may be proved wrong but as science is not dogmatic, it helps to correct and rectify it's own mistake while religion cannot tolerate even a slight deviation from their doctrine. That's why science is great.