Bus is cheaper while subway is faster. As for the details, please please see the chart above by yourself, ok?

Mr. hendra:
To take subway is the cheapest and fastest way to arrive at the Temple of Heaven. You will start from the Tiananmen East or West Station to Dongdan, and then change to line 5. Get off at Tiantan East Gate Station.
For bus, you could get on bus No.120 from Tiananmen East Stop to the Tiantan West Stop.
Both are all right for you.