Gosvāmī or svāmī, the same meaning: one who has been able to control the senses. Generally everyone is controlled by the senses. When one becomes controller of the senses, then he is gosvāmī. So generally we give this designation to the sannyāsīs, because sannyāsa means who has fully controlled all the senses. One should not accept sannyāsa whimsically. One must know about himself how far he can control the senses. Therefore generally sannyāsa is not accepted until one is sixty years old.
But in this age there is no guarantee whether we are going to live up to sixty years old age. So sometimes, younger generation also offered sannyāsa, because Caitanya Mahāprabhu accepted at the age of twenty-four years. We are not of course imitating Caitanya Mahāprabhu, but for executing Caitanya Mahāprabhu's mission, if we are sincerely working for Him, then we can take sannyāsa at an early age. That . . . when one is actually a sannyāsa, a sannyāsī, master of the senses, he can be addressed as gosvāmī or svāmī.