I'm hoping this is a serious question.
A drum machine is just that, a unit which reproduces percussion (particlarly) drum sounds.
An arpegiator, would be a unit or patch that takes a chord apart and plays it in succession up or down a particular scale.
That said..he may have been referring to tuned drums, that's all I can suspect.
The two (drum machine & arpegiator) are as different as night and day.
This salesman sounds a little strange to me...sort of like asking a car salesman if the vehicle has fuel injection and he says "No...but it does have power windows!" ...Huh?
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...shboom
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...shboom