How does Portia and Brutus' relationship differ from that of Calpurnia and Caesar?

The difference can mainly be seen in Act II, scene i (Brutus and Portia) and Act II, scene ii (Caesar and Calpurnia).

Portia talks to Brutus as though she were his equal, which was uncommon at the time. Wives were barely more than property and were to obey their husbands. However, Portia calls Brutus on his behavior: he's been moody, unresponsive and is now unable to sleep and walking amid the rain in their orchard in the middle of the night. When he orders her to go to bed, and tells her he is simply ill, she refuses and tells him that he's too smart to be outside in the rain if he is ill. Portia then tries to convince Brutus to tell her what's on his mind, using guilt and trying to prove how mentally and physically strong she is. She also insists that he took her as a partner, so by the right of her position, she should know what's on his mind. We can tell by Act 2, scene iv that he does tell her.

In contrast, Caesar and Calpurnia's relationship is more typical of Roman marriages. While Caesar listens to his wife's concerns about not going out of the house that day, he ultimately makes the decision to leave the house, calling her dreams and warnings foolish. He is in charge of the relationship. In Act 1, scene i, Calpurnia's only line is "Here, my lord", showing her obedience to him.