What is the difference between silver, vesicular & diazo microfiche?

 
What is the difference between silver, vesicular & diazo microfiche?
 
Silver - is a 4mil polyester base treated with silver gelatin to conform to ANSI/NAPM standard IT 9.1 and ANSI/AIIM MS5.

Vesicular - is on 4.3mil polyester base and conforms to ANSI/NAPM standard IT 9.12

Diazo - is on 4.3mil polyester base and conforms to ANSI/NAPM standard IT 9.5