What is the Difference Between findAndModify and updateOne in MongoDB?

I need to update documents in my MongoDB collection, but I'm confused about when to use findAndModify versus updateOne. What are the primary differences between these two operations, and which one is better for atomic updates?

Comparison Breakdown

Both methods perform atomic operations on a single document, but they differ in what they return and how they behave:

• Return Value: findAndModify returns the modified or pre-modified document, whereas updateOne returns a write result object with modification statistics.
• Performance: updateOne is generally faster and lighter when you do not need the original or updated document payload back.
• Modern Drivers: Modern drivers wrap findAndModify under helper methods like findOneAndUpdate.

Example: Returning Updated Document with findOneAndUpdate

db.counters.findOneAndUpdate(
    { _id: "orderId" },
    { $inc: { seq: 1 } },
    { returnDocument: "after" }
);