Moan sound (PURR) will use the time to show that happy might show symptoms of rolling back and forth or remove Chin rubbing sound while coming or cats injured and ill but is long and continuous sound than normal.
Moan (PURR) is used to express the joy. Symptoms may occur or be rolled over to rub his chin, while the ring. Or cat sick and injured badly. But it is a long and continuous than normal.
Groan (PURR) is used to express the time happily. May show signs of rolling, rubbing his chin, or the sound. Cat or injury and illness. But the sound is long and continuous than usual.