I am not a native korean but I think I can help :) sunbae = senior hoobae = junior in general : sunbae means people who are on upper grade than you and it is a word that refers to people with more experience (at work, school, etc), ex: if you are kpop fan so you know that super junior debuted in 2005 and mblaq debuted in 2009 . super junior debuted before so mblaq memebers will call suju members "sunbae" +nim = more polite ... the same as hyung and hyunmin and ofcourse it's not only about kpop

sunbae mean the person who have much informathion and he learn from his life