Jocasta believes that humans can make their own destiny, while the Chorus holds true to the traditional Greek belief that the gods are in charge of everything and human beings are but the pawns of their whims. It is only by following the signs and precepts of the gods and by making sacrifices to them that human beings can have a good life.
Beginning at line 864, the Chorus says:
May destiny ever find me
pious in word and deed
prescribed by the laws that live on high:
laws begotten in the clear air of heaven...
for God is great in them and grows not old.
And, a bit later:
If a man walks with haughtiness
of hand or word and gives no heed
to Justice and the shrines of Gods
despises -- may an evil doom
smite him for his ill-starred pride of heart!
Jocasta, on the other hand says that oracles are bunk and she, herself, believes that she can outwit an oracle, can outwit the will of the gods through her own actions. She gives her baby away after an oracle has predicted doom upon him, thinking that this will prevent the oracle coming true. When she finds out that she was not, as she had hoped, able to outwit the will of the gods (She realizes that the doom foretold has all come true in the person of Oedipus), she commits suicide.
So, while the Chorus conservatively pays tribute to the gods and their oracles, Jocasta believes that she can beat them at their own game, yet finds out, in the end, that the will of the gods and their oracles cannot be escaped by Man.