They are alike and not alike. But have the same consequence

Alike: Both need extra piston moves; Both cost extra money; both get hotter and hotter with the piston work; both make sound when the piston works.

Not Alike: One uses your own piston, the other does not; One can only work for limited time, the other can last very long; One is already hot when piston gets there, the other is old when piston starts to work; One gets more and more lubricaton as the piston works more and more, the other bascally the same no matter how hard the piston works.

Same consequence: The owner gets the comfort...