Opening is related to Operation. Operation is related to Medicine. Medicine is related to Herb. 
Differ is a synonym of Disagree. Disagree is related to Protest. Protest is the opposite of Accept. Accept is the opposite of Refuse. 
Opening <--RelatedTo--> Operation <--RelatedTo--> Medicine <--RelatedTo--> Herb 
Differ <--Synonym--> Disagree <--RelatedTo--> Protest <--Antonym--> Accept <--Antonym--> Refuse 