Buddha, god, fairy, bodhisattva, arhat. What are the grades?

These five titles are not in the same system, in which God and Immortal belong to the Taoist system, while Buddha, Bodhisattva and Lohan belong to the Buddhist system.

For the two titles of God and Immortal:

God and Immortal can't clearly distinguish whose realm is high. This is because the scope of God is the widest: gods and ghosts are all included under the general name of "God". Among the gods, there are high-level gods such as "God of Heaven" and "True God", and there are also folk gods such as "Kitchen God" and "God of Wealth" whose level is not too high. "Immortal" refers to Taoist immortals who have special abilities and are old and immortal.

As for the three titles of Buddha, Bodhisattva and Lohan:

The titles of Buddha, Bodhisattva and Lohan are in descending order, and Buddha refers to an enlightened person whose wisdom and understanding have reached the highest level. The realm of Bodhisattva is inferior to that of Buddha, and what Bodhisattva has achieved is only the superior realm in Mahayana Buddhism. Lohan is a high-legged disciple of Buddha. Lohan's spiritual realm is below Buddha and Bodhisattva, and above monks, Lohan's cultivation is only the highest realm in Hinayana Buddhism.

Extended information:

Taoism and Buddhism-related culture

Taoism: Taoism is a local religion in China, with "Tao" as its highest belief. Taoism, on the concept of worship of ghosts and gods in ancient China, is based on the thoughts of Huang and Lao Taoism, and inherited the immortal magic since the Warring States Period. Taoism is a polytheistic worship, and worshipping immortals personifies Taoism's belief in "Tao".

Taoism is widely spread in East Asia and Southeast Asia. Japanese Shintoism, Emperor belief and folk belief are deeply influenced by Taoism. Korean Tiantai Taoism and Vietnamese Gaotai Taoism are new religions formed on the basis of Taoism, and Taoist Quanzhen Sect is an important religion in Singapore and Malaysia.

Buddhism: Buddhism has a history of more than 2,5 years. It was founded by Gautama Siddharta, the prince of the ancient Indian kingdom of Kapilowei (now Nepal). Buddhism attaches importance to the progress and consciousness of human mind and morality. The purpose of practicing Buddhism by Buddhist believers is to discover the truth of life and the universe according to Siddhartha's practice methods, and finally transcend life and death and suffering and get relief.

Baidu Encyclopedia-Buddhism

Baidu Encyclopedia-Taoism