Yesterday a student of mine had a question for me: when saying "my older brother" or "my elder brother", which is better?
Elder is a comparative form, which means the elder of two people, especially brothers and sisters, is the one who was born first. See the following sentence:
My elder brother always finds faults with what I did.
I am the elder of the two.
However, it is more usual to say older. In such case, elder can be replaced with older.
My older brother always finds faults with what I did.
I am the older of the two.