(1) It can be seen from the three pictures of A, B and C that A and B vibrate the same number of times in the same time, so their vibration frequencies are the same. So the pitches of A and B are the same; the amplitudes of the waveforms of B and C are the same, so their loudness is the same.

(2) Sound is produced by the vibration of objects, so picture A shows that the object making the sound is vibrating;

The swimmer in picture B can hear the music on the shore underwater. Sound, indicating that sound can spread not only in the air, but also in water;

In picture C, the little white rabbit can tell that the person calling the door is not grandma, based on the timbre of the sound.

So the answer is: (1) A and B; A and C;

(2) Vibration; water; timbre.