What are the features of differences in the structure of internal organs and behavior of birds

What are the features of differences in the structure of internal organs and behavior of birds, indicating a higher organization of these animals in comparison with reptiles?

Reptiles and birds are very similar in origin. They belong to vertebrates, so they have a lot in common. It is not only the presence of a spine and a similar skeleton. Both are capable of laying eggs. But birds are more advanced. They have a more developed circulatory system. Their heart is four-chambered. Also, birds are warm-blooded, unlike reptiles. Birds have their own characteristics of behavior, but they depend on the specific type of bird and certain environmental conditions.