Gang is related to Tough. Tough is a different concept from Hard. Hard is the opposite of Nice. 
Staff is related to Servant. Servant is related to Slavery. Slavery is a type of Practice. Practice is a synonym of Commit. 
Gang <--RelatedTo--> Tough <--DistinctFrom--> Hard <--Antonym--> Nice 
Staff <--RelatedTo--> Servant <--RelatedTo--> Slavery --IsA--> Practice <--Synonym--> Commit 