Memory is a different concept from Disk. Disk can be used for Storage. 
Achieve is related to Get. Get is a synonym of Drive. Drive is related to House. House is related to Road. 
Memory <--DistinctFrom--> Disk --UsedFor--> Storage 
Achieve <--RelatedTo--> Get <--Synonym--> Drive <--RelatedTo--> House <--RelatedTo--> Road 