сморкаться/сморкнуться: generally just refers to the action of blowing your nose, with no particular emphasis on how thoroughly or completely the action is done. вы́сморкаться and вы́сморкнуться: also means "to blow one's nose," but has an added nuance that emphasizes the complete or thorough clearing of the nose, often suggesting a more deliberate or thorough effort. (The prefix "вы-" adds an idea of "out" or "completely")