Hard is related to Coin. Coin is related to Disc. Disc is related to Permit. 
Tight is similar to Secure. Secure is related to Safe. Safe is related to Bank. 
Hard <--RelatedTo--> Coin <--RelatedTo--> Disc <--RelatedTo--> Permit 
Tight <--SimilarTo--> Secure <--RelatedTo--> Safe <--RelatedTo--> Bank 