First, the meaning is different.
1. Big brother means: Big brother.
2. Brother means brother
Second, the usage is different.
1.old brother Usage: brother means "brother" or "brother", and "brother" means "elder? Brother ","brother "is" brother? Brother.
But except when it is necessary to distinguish between "brother" and "elder brother", it is customary to use "elder brother" regardless of "elder brother". Elder is not commonly used in America? Brother, not old? Brother. The feminine noun corresponding to brother is sister.
2. Usage of elder brother: Elder brother can refer to a blood-related brother, half-brother or half-brother, or the son of stepfather and ex-wife or stepmother and ex-husband, not a cousin. But extension can refer to "peers and colleagues". When a brother explains "brother" and "member", its plural form is brother.
Third, the emphasis is different.
1. Brother Focus: Focus on this brother's old state.
2. Brother Focus: Focus on the fact that family members are brothers.