What is the difference between findOneAndUpdate and update?
Both accept criteria to query and doc to update.
Well there is the respective documentation to view for both .update() and .findAndModify() which is the root method of .findOneAndUpdate() here.
But in the main differences there are:
update(): Is meant to perform an atomic update operation against "one or more" documents matched by it's query condition in a collection. It returns the number of modified documents in it's response.
findOneAndUpdate(): Has the purpose of both processing an update statment on a "singular" document, as well as retrieving the content of that "singular" document. The state returned depends on the value of the "new" option as passed to the operation. Where true the "modified" document is returned. Where false the "original" document is returned before any modification. The latter form is the default option.
In short. One is meant to modify in "bulk" and not worry with the document content in result. And the other is meant to modify a singular document and return the document content in result.
That's the difference.