Is nursing a profession or vocation?

A vocation is, to the best of my understanding, what God calls you to. It is the career or profession that God wills for you. Nursing is certainly a profession, but most people only consider a profession in the Church a "vocation."

The Catholic Church's stance on this, if i can speak for It, is that all people are called to witness to Christ and the Church. So, in whatever you do you should always be doing it for the greater glory of God, as St. Ignatius would say.