What's the difference between Tian and Yao?

One is simplified and the other is traditional. It is the same word, and there is no difference.

Traditional Chinese characters, a font form of Chinese characters, are called "traditional Chinese characters" in European and American countries. Generally speaking, it refers to the Chinese characters replaced by simplified characters in the Chinese character simplification movement, and sometimes it refers to the whole Chinese character regular script and official script writing system before the Chinese character simplification movement. Traditional Chinese has a history of more than two thousand years. Until 1956, it was the standard Chinese character used by Chinese people all over the world.

In addition to their own glyphs, traditional Chinese and simplified Chinese are also different in vocabulary. For example, the ballpoint pen commonly used in simplified Chinese is called ballpoint pen in traditional Chinese, Stalin in simplified Chinese is called Stalin in traditional Chinese, Korea in simplified Chinese is called Korea in traditional Chinese, and Sydney in simplified Chinese is called Korea in traditional Chinese.

Because of this difference, the term "traditional language" came into being. But in fact, this is not the difference between traditional Chinese characters and simplified Chinese characters, mainly because people who use them, especially Chinese mainland and Taiwan Province Province, did not communicate much after their separation for political reasons in the middle of the 20th century, which resulted in the differences in word usage habits.