The Tang dynasty ruled for 289 years. During that time their armies conquered a lot of territory. Vietnam, Tibet, and Korea are some of the places they conquered. The Chinese army forced these territories to become tributary states. They also rebuilt the bureaucracy and enlarged the civil service system.
The Song and Tang dynasties both had well organized societies. They both also had very many poets and artists. The poets works reflected Buddhism and Daoism. During both dynasties the foreign trade flourished. The canals and waterways made it easier for other traders to reach the Chinese.
The Song dynasty ruled for 319 years, a slightly longer time then the Tang. During the Song period they had military setbacks. After constant threat of invasion in the north, the Song moved south. They didn't rule as much land as the Tang. Still under the Song rule the Chinese economy expanded.
Those are some of the similarities and differences in the Tang and Song dynasties.