All Brahmanas are no Rishis and vice versa...also there r many types of rishis like Rishi, Rajrisihi, Maharishi, Devarishi, Brahmnrishi etc... Related https://hinduism.stackexchange.com/a/22866/12304
– YDSAug 16 '22 at 03:04
Brahmana is one who possesses the qualities of truthfulness, generosity, forbearance, good conduct, total absence of cruelty, self-control and compassion(Nahusha Prashna, Mahabharata). with a conviction that
the only truth that is worth knowing is the supreme Brahman.(Thus called Brahmana)..Shad karma of a Brahmana are Adhyapanam,Adhyayanam,Yajanam,Yaajanam, Dhaanam,Prathigraham.
A Rishi is one who has acquired spiritual wisdom, enlightment (Brahma nishta). Rishi is explained in
http://www.hindupedia.com/en/%E1%B9%9A%E1%B9%A3i
– AthreyAug 16 '22 at 15:34
A Brahmana is a fellow of the Brahmin caste. Brahmins do not inherently have divine knowledge. A rishi is a knower of mantras, a term often ascribed to knowers of divinne knowledge. You do not to be a Brahmin to be a rishi.
– Swami VishwanandaAug 18 '22 at 05:26