웃다 = to laugh (someone laughs) 웃기다 = to make someone laugh (someone causes laughter)
Example Sentences:
친구가 재미있는 이야기를 해서 웃었어요.(My friend told a funny story, so I laughed.)
이 코미디언은 정말 웃겨요!(This comedian is really funny!)
그는 항상 사람들을 웃게 해요.(He always makes people laugh.)
웃다 is an action you do, while 웃기다 is what makes you laugh! 😊