As friends, the young boy is friendly and kind to the old man and the old man is the same, but they are both different in a variety of ways. An obvious reason is the fact that there is an age difference present in both people. Another example is how the old man doesn't see himself as a worthy person, while the boy is confident about his life and feels that his friend is a father to him. Their thoughts are different when one looks at both the old man and the boy. Then it comes to physical differences between both people. Of course, the old man is weak and he can't do some things as well as in the past. This proves to be true in the situation when the old man is hunting for the fish and he stumbles trying to capture that fish. In that type of situation, the boy could help by using his strength, but he wasn't there at that time and the old man could only wish for him to be there. These contrasted characteristics of the old man and the boy are both in physical and mental differences.
The sea can be like a person when it has some obstacles along the way and it seems like it has a mind of its own. Not only did the old man have differences among people, but with objects as well and that is the sea. The sea can control the old man's boat and his physical labors. This will give the sea characteristics and it basically represents a character in the book. After all, the sea is the main setting and obstacle for the old man. Also, the old man is powerless against