Whey they both mean make something clean or kill bacteria
Both words are used to refer to the process of making something cleaner.
However, if we delve deeper into the scientific community, sterilization has a higher emphasis on eliminating all microorganisms. Sterilization has a higher scrutiny to it. For example, I know research labs that would still sterilize brand new apparatus that just arrived. The typical way to sterilize apparatus is to autoclave them, which means to subject it to high heat and pressure for optimal sterilization.
Despite the apparatus arriving in a seemingly pristine condition, know that some experiments are highly sensitive to external variables such as the presence of microorganisms. And having worked as a lab assistant myself, we have never used the term "disinfect" when referring to cleaning something relatively clean, such as brand new equipment.
To put things simply,
sterilization has a higher emphasis for complete removal of microorganisms and
disinfection tends to be the better word when trying to make already contaminated surfaces clean.