There are several steps in the Church’s process of declaring someone a saint. From first to last, the corresponding titles are Servant of God, Venerable, Blessed, and Saint. “Blesseds” are those who have been beatified. Beatification requires one attested miracle and allows the beatified person to be venerated by his local church. Canonization requires two attested miracles and allows veneration of the saint by the universal Church. Canonization is an infallible statement by the Church that the saint is in heaven.
For more on how the Church canonizes, see our encyclopedia entry “Beatification and Canonization.”