I don't think they are synonyms:
Paging doesn't necessarily mean pagination in computing:
From the Wikipedia article on Paging
In computer operating systems, paging is one of the memory-management
schemes by which a computer can store and retrieve data from secondary
storage for use in main memory.
Paging can refer to the act of reading data tables page by page (credit to @Ian Ringrose)
Paging can refer to the act of sending data to a pager (credit to @Al Everett)
...where as pagination is to divide up copy into pages, as one might do when designing a UI.