What's the difference between stars and stars in a perpetual calendar?

The stars in the solar calendar are also called twenty-eight nights. It originated very early and was first used by the ancients to observe the movement of the sun, the moon and the five stars. After long-term observation, the ancients chose 28 stars near the equator of the ecliptic as coordinates, which were called 28 nights. The ancients took turns keeping diaries for 28 nights, with one night representing one day and starting again on Sunday, with 28 days as a cycle. It is divided into East Seven Nights, West Seven Nights, South Seven Nights and North Seven Nights. It is also to determine the quality of one night and judge it with 28 nights. The representative works about choosing good or ill luck include Xie Fang Shu and Ji Ji Hui.

Star god is the god in charge of the stars in the sky.