The Difference Between מתעסק and שוגג
Rabbi Sruly Bornstein
R' Chaim Brisker's difference that Misaseik is someone who had in mind to do one thing, and ended doing something else, while Shogeg is someone who had in mind to do something and he did what he had in mind to do, but he didn't realize what he was doing was assur. Sugya: מצות צריכות כוונה