He has a remarkable ear for intonation, a great sense of rhythm and what is most important, he has great style - style in my way of thinking is a mat… - Fred Astaire

The major difference between Astaire and Kelly is a difference, not of talent or technique, but of levels of sophistication. On the face of it, Kelly looks the more sophisticated. Where Kelly has ideas, Astaire has dance steps. Where Kelly has smartly tailored, dramatically apt Comden and Green scripts, Astaire in the Thirties made do with formulas derived from nineteenth-century French Farce. But the Kelly film is no longer a dance film. It's a story film with dances, as distinguished from a dance film with a story. When Fred and Ginger go into their dance, you see it as a distinct formal entity, even if it's been elaborately built up to in the script. In a Kelly film, the plot action and the musical set pieces preserve a smooth community of high spirits, so that the pressure in a dance number will often seem too low, the dance itself plebeian or folksy in order to "match up" with the rest of the picture.

(Cary Grant) is, along with Fred Astaire, the best-dressed actor in American movies

Except for times Fred worked with real professional dancers like Cyd Charisse, it was a twenty five year war.