Slave is related to Master. Master is a different concept from Servant. Servant is related to Middle. Middle is related to Seed. 
Senate is a different concept from Congress. Congress is related to Committee. 
Slave <--RelatedTo--> Master <--DistinctFrom--> Servant <--RelatedTo--> Middle <--RelatedTo--> Seed 
Senate <--DistinctFrom--> Congress <--RelatedTo--> Committee 