Is there a difference between motorcycle turn signal lights and car turn signal lights?

Sometimes yes and sometimes no. If the bulb numbers match (such as a common 1157 turn/stop bulb), then they are completely interchangeable. If they don't match, they probably are not interchangeable, since automobiles typically use 12 volt batteries and at least some motorcycles use 6 volt batteries. Also, many bulbs use unique bases that will only allow them to be used in the correct socket.