كَبِيرِ الْإِخْوَةِ identifies the elder brother. Respect includes listening with consideration, offering help when needed, and handling disagreements without insults.
The elder brother, in turn, should protect younger siblings' dignity and rights. Seniority should not be used as a means of domination.
The wording makes a comparison with a father's rights to stress the importance of respect. It does not necessarily make every legal obligation toward a father and an elder brother identical.