centralization vs consolidation

centralization

noun
  • The act or process of centralizing, or the state of being centralized; the act or process of combining or reducing several parts into a whole 

consolidation

noun
  • The act or process of consolidating, making firm, or uniting; the state of being consolidated 

  • The combination of several actions into one. 

  • A solidification into a firm dense mass. It is usually applied to induration (swelling or hardening of normally soft tissue) of a normally aerated lung. 

How often have the words centralization and consolidation occurred in a corpus of books? (source: Google Ngram Viewer )