Government & poli sci (& IS/IR/IA) might have different dictionary definitions, but when it comes to academic departments they are like hoagie, hero, submarine sandwich…or hot dog, frankfurter: different names for the same thing.
It’s possible someone will claim some miniscule technical difference among hoagie/hero/submarine , and certainly there are differences even among submarine sandwiches.
My point is nobody orders a frankfurter & when a hot dog arrives, says, “Hey! I ordered a FRANKFURTER!” No restaurant’s menu has Heros listed on one page & Hoagies on another. No college has a Dept of Governent over here, & a Dept of Political Science over there. Same with International stuff.