What is the difference between Buddha, Bodhisattva, Arhat?

Many people who believe in Buddhism sometimes always say how good our Buddhism is, but ask them the most basic question, Buddha, Arhat, Bodhisattva, what is the difference, even the 9th layer people do not know. First Buddhism was born in ancient India, where a prince named Gautama Siddhartha. Chinese professionally called him Shakyamuni, and the folk called him Buddha or Buddha. He saw the people of the world suffering in all kinds. Therefore, for the sake of the people, he practiced on his own to find a way not to let the people suffer, and finally meditated under a Bodhi tree to become a Buddha. (Explained in this way, sitting and thinking about the problem, in the end many questions are figured out with various ideas or methods, that is, to see through life, and when he thinks through, he thinks that it is expressed by the word becoming a Buddha, in fact, Buddhism is the scripture in Buddhism now is actually a philosophy). Then he taught these methods to the people, called spreading the Dharma, and now the monks in the temple are also called The Dharma when they preach the scriptures to the people. Then others began to worship him as a god, but he himself said that I was a man and not a god, that I was only preaching the Dharma, not creating a church, and not worshiping me. So it wasn't until 500 years after his death that there was an image of the Buddha, Buddhism. Because people at that time considered that there was no orthodox sect, the Dharma could easily be lost. Then thousands of years of form spread to various Asian countries, we in China is Tang Sanzang went to the Western Heavens to learn the scriptures. It is to take the Dharma and popularize it to the Chinese people. So a Buddha means that a person who has figured out the philosophy of life is called a Buddha. The disciples he taught later figured it out, and they were also called Buddhas. But in order to separate them from their teacher Shakyamuni, the distinction between the honorable teachers is generally called arhat. So Buddha = Arhat. But bodhisattvas are those who have become Buddhas and those who have not yet become Buddhas, but who are helping to spread the Dharma. Some bodhisattvas have many disciples who have become Buddhas, but they are still bodhisattvas themselves. (It is similar to the master leading into the door, the practice depends on the individual, many disciples eventually surpass the master) So for Shakyamuni, he was both a Buddha and a bodhisattva.