What is different in using Pair and Couple?
They are all used to describe two items, people or animals.
Use “Pair” to talk about two very similar things that are matched together in a set, like:
‘A pair of shoes.’
‘A pair of pants.’
‘A pair of spectacles.’
Beside, ‘A couple’ describes two things that make up a partnership, or have something in common at that particular point in time.
‘There are a couple of people in the pool.’
‘There are a couple of birds on the jetty.’