What is the difference between upgrade and update in Drupal?

It's easy to understand, what is upgrade and update, please have a look.

Update: If Drupal gives minor change version like Drupal 8.0.1 to 8.2.0, so that is update.

Upgrade: If Drupal gives major changes version like Drupal 6 to Drupal 8 or from Drupal 7 to Drupal 8,  that is upgrade.

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