UX designer is an umbrella term covering UX researchers, UI designers, and product designers. The list may go on, but those are the most common roles.
UX design isn’t solely about looks. It has to rely on data to be effective. UX researchers don’t design much, but they collect information to drive design decisions and create data charts, personas, etc.
Next, good UX can be ignored without UI as it communicates identity and brand to the user. UI makes users decide whether they want to engage with the product. Hence, UI designers focus on appealing visuals rather than providing user experience services.
Product designers are good at everything. They participate in creating every aspect of the product, offer UI and UX services, and contribute to its information architecture.
However, it’s often difficult to differentiate between specific roles because most designers do a little of everything. Therefore they choose to go by the collective term “UI/UX,” meaning you can give them all kinds of tasks.