I can maintain polite conversation.
One is a bunch of Cunning Stunts
One goes quick on her beautiful legs the other goes quack on her beautiful legs.
An erection.
When you wake up in the morning with an erection so stiff, that when you bend it down to take a leak, your legs kick back and you hit your head on the toilet.
One costs a lot of money to maintain, keep running, and give you the results you want. The other has four wheels.
Hardware breaks if you maintain it.