I am not able to find an accurate answer to this question. Are they the same?
Clarity of semantics. Arguably, the word refinement expresses the idea of continuous improvement a little better than grooming. The latter denotes removing defects or straightening out. Grooming also holds a connotation of a focus on appearances, as the Cambridge Dictionary's primary definition of grooming is:
the things that you do to make your appearance clean and neat, for example brushing your hair, or the things that you do to keep an animal's hair or fur clean and neat
Increased acceptance of framework terms. In British English, the same dictionary also defines grooming as:
the criminal activity of becoming friends with a child, especially over the internet, in order to try to persuade the child to have a sexual relationship
Words matter, and the change to a term that provides better clarity about the purpose of the ceremony while also avoiding negative connotations is a net positive. However, you may still find early adopters of Scrum occasionally referring to "backlog grooming" out of habit, even though the term has officially been changed.