Difference in Downloads and Installations count

I can find a huge difference in Total downloads and installations count in my app. Should I believe that there're only 8K users opening my app despite 23K downloads?

Any chances that cancelled downloads or failed downloads also include in this "downloads" count?

If you look very carefully, you'll see that the "installations" graph says "opt-in only" and the "total downloads" doesn't.

Difference in Downloads and Installations count
 
 
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