Brutus and Antony are two very different character types. Brutus spends much of his time alone. He is a philosopher, a reader, a thinker, an introvert. Antony, on the other hand, is an extravert, an athlete, and a fun-loving party-goer. He is depicted that way even in Shakespeare's Antony and Cleopatra, in which he ruins his reputation, his partnership with Octavius, and finally his life because of his addiction to eating, drinking, amusement and love-making.
Brutus, characteristically, makes a very solemn and logical speech to the mob. It is noteworthy that he talks about himself all the way through. Notice how many times he uses "me," "my," and "I" in the following excerpt. He is "the noblest Roman of them all," according to Antony at the end of the play; yet Brutus has at least one serious fault which leads to his downfall. He is not exactly proud, but locked up inside of himself, preoccupied with his own thoughts. He doesn't relate well to other people. This makes him an easy victim of men like Cassius and Antony, who are more cunning than wise, but who can see right through him and know how to manipuate him by appealing to his noble character and his noble family background. He wants people to love and admire him--but he does not necessarily love or admire anybody else. He can't help himself. That is his character. He spends too much time alone and too much time philosophising. When he is put in the position of leadership, he wants everything to be done his way and no other way. He becomes overbearing and insufferable. Since he won't listen to other people, he naturally makes serious mistakes.
Romans, countrymen, and lovers! hear me for my
cause, and be silent, that you may hear: believe me
for mine honour, and have respect to mine honour, that
you may believe: censure me in your wisdom, and
awake your senses, that you may the better judge.
If there be any in this assembly, any dear friend of
Caesar's, to him I say, that Brutus' love to Caesar
was no less than his. If then that friend demand
why Brutus rose against Caesar, this is my answer:
--Not that I loved Caesar less, but that I loved
Rome more. Had you rather Caesar were living and
die all slaves, than that Caesar were dead, to live
all free men? As Caesar loved me, I weep for him;
as he was fortunate, I rejoice at it; as he was
valiant, I honour him: but, as he was ambitious, I
Marc Antony, on the other hand, is a man of action and not a thinker. When it comes his turn to speak about Caesar, he pretends to feel humble and grief-stricken. He calls the plebians his "masters." He puts them in the forefront rather than himself. He doesn't have to try to justify his actions, like Brutus, because he did nothing and wasn't even present when Caesar was killed. Rather than talking about himself, he talks about Caesar, about Brutus, about the assembled mob, and about the other conspirators. He pretends to be reluctant to read Caesar's will because he believes it will infuriate his listeners--although that is exactly what he wants to do. He makes them force him to read the will, but before doing so he has them gather around the coffin so that he can show them the mutilated corpse. He understands people far better than Brutus, who has spent much of his life speculating about abstractions and about how he personally should think and act in this world. Not only can Brutus not understand other people, but other people cannot understand him. He is too intelligent, too learned, and too noble.