Easy is a different concept from Tough. Tough is similar to Uncomfortable. 
Guide is a type of Structure. Structure is related to Construction. Construction is related to Stage. Stage is a synonym of Arrange. 
Easy <--DistinctFrom--> Tough <--SimilarTo--> Uncomfortable 
Guide --IsA--> Structure <--RelatedTo--> Construction <--RelatedTo--> Stage <--Synonym--> Arrange 