그러네요 and 맞아요 are somewhat related but used differently. * 그러네요: (I see) that/it is so. Now I realize that. It comes from 그러하다(it/that is so) + -네 (an ending expressing a mild surprise). It expresses an acknowledgment or agreement with something the other person said. * 맞아요: That's right; That's true/correct. Its base form 맞다 has a stronger sense than 그렇다, that what's mentioned is the exact thing one has thought. it identifies something positively and emphatically true. - 오늘 영철 씨가 우울해 보여요. 그러네요 = Yeah, you're right. - 축구 시합에서 우리 팀이 이겼대요. 맞아요! = Yep! We sure did! (more emphatic and enthusiastic)