An older brother — a male sibling who is older than the speaker.
兄は医者で、東京の病院に勤めている。
My older brother is a doctor and works at a hospital in Tokyo.
子どものころ、兄とよくサッカーをした。
As a child I often played soccer with my older brother.
あの人は私の兄です。名字は山田です。
That person is my older brother. His family name is Yamada.
Brother-in-law (specifically an older brother by marriage) — e.g., a spouse's older brother or an older sister's husband.
結婚してから、妻の兄（＝義兄）と親しくなった。
After getting married I became close with my wife's older brother (my brother-in-law).
彼は義兄だが、普段は『兄さん』と呼んでいる。
He is my brother-in-law, but I usually call him 'niisan' (brother).