What is the difference between ox and oxen?

Could you please clarify the distinction between the terms "ox" and "oxen"? I understand that they both relate to bovine animals, but I'm not entirely sure how they differ from one another. Is "ox" referring to a single animal, while "oxen" is a collective noun for multiple oxes? Or is there a more nuanced difference between the two terms? I'd appreciate any insight you can provide on this topic.