I don't think border is only used in contexts such as border conflict.No.2
Portugal only has ________ with Spain, since Macau went to Chinese administration by the end of 1999.
a. frontier b. border
The key is 'a'. 'border' is only used in contexts such as 'border conflict' etc. Is that right?
According to Collins:
"The border between two countries or regions is the dividing line between them. Sometimes the border also refers to the land close to this line.
They fled across the border.
...the isolated jungle area near the Panamanian border...
Clifford is enjoying life north of the border.
...the Mexican border town of Tijuana...
So according to my dictionary, border and frontier have the exact same meaning.
Here's one small difference you might find interesting.
Here's what I found for the definition of frontier:
A frontier is a border between two countries. (BRIT; in AM [America], usually use border)
So from what I make of it:
British English: Frontier
American English: Border
"It wasn't difficult then to cross the frontier."
I would like to know why A is any better than B in your example. From what I can tell, it's only a cultural differences expressed through language.
Like traveling (American) and travelling (British).
Student or Learner