Difference between hook_entity_presave and hook_entity_insert ?

Simple way to differentiate both hooks is the 'ID' is not available in hook_entity_presave() ("pre meaning before, and without saved ID is not assigned in database),
But this 'ID' will be available in hook_entity_insert().

Example:
function mymodule_node_insert(NodeInterface $node) { 
  $nid = $node->id();
}
OR
function mymodule_node_insert($node) {
  if ($node->getType() == 'your content type') {
        $node->setTitle('New entity ' . $node->id()); // to update title with node id
        $node->field_test = 'Id' . $node->id();  // or, to update a text field with node id
        $node->save();
  }
}

function mymodule_entity_presave(Drupal\Core\Entity\EntityInterface $entity) {
  if ($entity->getEntityType()->id() == 'node') {
    $entity->setTitle('New Title here');
    //Note : Not to save, because it's automatic.   
  }
}
OR
function mymodule_node_presave(Drupal\node\NodeInterface $node) {
  $node->setTitle('Edited Title');
  $node->set('body', 'this is the new body section');
  //Note : Not to save, because it's automatic.
}

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