Leather oil is a type of leather conditioner. There are many different types and formulations available. Some cater to specific leather products (shoes, boots, bags, etc.). Others to the conditions the leather will be used in. And even others that have more general formulations that work well on most leathers.
Leather oils can be just oils, or combinations of oils, waxes, and other natural and/or synthetic ingredients aimed at conditioning and protecting the leather. Definitely read up on the particular oil you might choose, reviews of it’s performance, and how well it will work for your specific leather application. With the right oil/conditioning, the leather will look and feel amazing.