I believe you mean Act II, scene 1.
Both Puck and the Fairy are minions, although Puck seems to be Oberon's right hand man, so to speak. He brags about his tricking mortals. He seems to delight in the misfortune of others, especially if he can be a part of that misfortune. The Fairy seems to know and recognise him.
Oberon and Titania, on the other hand, are very powerful beings who rule the forest and the world of the night. They have been quarrelling about a young boy, aka the changeling child. Oberon believes that it is time for the boy to live in the world of men. A young noble male child would begin his training with the women as a page. Entering puberty is was time for him to learn in the world of men as a squire and finally he would become a knight. Each of these terms are mentioned. Puck says Oberon wants the boy to become a knight of his train. Titania calls him her young squire and Oberon refers to him as her page.
The result of their quarrelling has affected the world of mortals as Titania describes in her speech concerning their effect as their parents and originals.
When Oberon observes Helena's plight with Demetrius, he wants to help her. This is in contrast to Puck who delights in tricking mortals.