The two are very closely related, but they are not synonymous. The refusal to submit to what one truly believes to be God’s Will, is, in serious matters, a mortal sin. But if we choose the “wrong” path, God can use our mistakes; He can re-direct us. There is always room for repentance and re-modelling, so to speak.
Most importantly, we should ask for the grace to know and love His Will. Such a prayer cannot fail to be answered, even if it takes time.* Some* uncertainty might be present (perhaps for an indefinite period of time); this is often a part of faith.
Some pertinent quotes from St. Alphonsus:
"But if you entreat him with indifference and resolution to follow his will, God will make you know clearly what state is better for you."
“You will answer me: “How can I be content, if I was not called to this state?” But what does it matter if at the beginning you were not called? Although you did not become a nun by divine vocation, it is nevertheless certain that God permitted that for your welfare; and if he did not call you then, at the present time he certainly calls you to belong completely to him.”
(A quote for those discerning a religious vocation):
“There is a true vocation whenever the following three things concur. First, a good end, namely, to get away from the dangers of the world, the better to insure eternal salvation, and to unite oneself more closely to God. Secondly, that there is no positive impediment due to poor health, lack of talents, or some necessity on the part of one’s parents, in regard to which matters the subject ought to quiet himself by leaving all to the judgment of the superiors, after having exposed the truth clearly. Thirdly, that the superiors admit him. Now, whenever these three conditions are truly present, the novice ought not to doubt that his vocation was a true on.”