Good morning
Thanks my dear Alaa for your nice question
I think there are 3 vocabularies that have approximatively the same meaning, but they are different actually
Overseas: this term is related to countries across the sea
Abroad: this one can be referred to crossing a main land
Outside which is more global, we can say outside home, outside the classroom, outside the
...country
I hope I'm right but let's ask Joe to be sure, and I invite my Friends to shed lights on this topic
Have a blessed day