Operator is a synonym of Function. Function is related to Memory. Memory is related to Think. Think is related to Process. 
Similarity is the opposite of Difference. Difference is a different concept from Equality. 
Operator <--Synonym--> Function <--RelatedTo--> Memory <--RelatedTo--> Think <--RelatedTo--> Process 
Similarity <--Antonym--> Difference <--DistinctFrom--> Equality 