-al vs -y

-al

suffix
  • Of or pertaining to. Adjectival suffix appended to various words, often nouns, to make an adjective form. Often added to words of Latin origin, but used with other words also. 

  • Forms the names of aldehydes. 

  • Forming nouns, especially of verbal action. 

-y

suffix
  • Added to nouns and adjectives to form adjectives meaning “having the quality of”, either “involving the referent” or “analogous to it”. 

  • Added to verbs to form adjectives meaning "inclined to". 

  • Used in the name of some locations which end in -ia in Latin. 

  • Forming abstract nouns denoting a state, condition, or quality. 

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