If you define poetry as
> [a] variable literary genre characterized by rhythmical patterns of language
(from L. Kip Wheeler's glossary of literary terms), you get a very broad definition that also covers epic poetry, e.g. Derek Walcott's _Omeros_ (1990, the most recent example I'm aware of) and verse drama, e.g. Mike Barlett's King Charles III (2014). (I mention these recent examples to show that these genres are not really dead or can be revived at any moment.)
Epic poetry and verse drama cannot simply be reduced to "giving different names to the same thing". Since they are examples of poetry, poetry in general cannot be reduced to "giving different names to the same thing".