홀로 - alone 외로운- lonely 혼자 - by oneself 쓸쓸하다 - lonely, solitude(?) 고립시킨다 - be segragated 격리하다 - segragate, isolate If I translate these into english, some of them mean very silmilar. For example, (홀로 & 혼자) and ( 외로운&쓸쓸하다) etc. They both mean almost the same but their usage and nuance are different. So I think to really understand the difference. You have to know when and how they are used.