Azure and Blue-gray

Azure adjective - Of a deep somewhat purplish blue color similar to that of a clear October sky.

Blue-gray and azure are semantically related In some cases you can use "Blue-gray" instead an adjective "Azure".

Blue-gray adjective - Of grey tinged with blue.

Azure and blue-gray are semantically related in sky topic. You can use "Azure" instead an adjective phrase "Blue-gray".