A conflict arising between any two persons like in between siblings can be referred as relationship conflict, man versus man or external conflict.
Explanation:
The conflicts between siblings are usually due to
Competence, achievements or over-performances of one over another
Receiving unequal amount of attention from parents and others
Personal, physical, or psychological issues
Conflicts arising due to achievement differences often lead to inferioritycomplex in the less achieved person and superiority complex in the high achieved person.