Most of the subjects are the same, and aerospace graduates are going to be able to apply to mechanical engineering jobs and vice versa.
Aerospace tends to view subjects through a more focused lense, whereas there is more variety in mechanical. For example fluid mechanics: in aerospace you’ll do aerodynamics whereas in mechanical you could do a wide variety of fluid-body interactions.
Aerospace also encompasses more on avionics however the physics and theory is the same at the end of the day.
The only thing that may well come up in an interview is demonstrating industry specific knowledge and interest. Most of which is learnt from personal research anyway.