Both are the honorific forms of "에게(or 한테)" and subject particles "이/가" repectively.^^/ Here are examples of them. I wrote a letter to my mother. = 나는 엄마+한테 편지를 썼다(not polite and intimate) = 나는 어머님+께 편지를 썼다.(polite) My mother wrote back to me. = 엄마+가 답장을 보냈다.(not polite and intimate) = 어머님+께서 답장을 보내셨다.(polite) \^o^/