center of attention vs centre of attention

center of attention and centre of attention both are nouns.

Word	Noun	Adjective	Verb	Adverb
center of attention	Yes	No	No	No
centre of attention	Yes	No	No	No

As nouns, center of attention and centre of attention are synonyms defined as:

center of attention and centre of attention: the object upon which interest and attention focuses

Other synonyms of center of attention include center, centre.

center of attention (noun)	centre of attention (noun)
the object upon which interest and attention focuses	the object upon which interest and attention focuses