To me, the difference is in how the propulsion is applied. If you have to pedal to get forward motion, and the attached motor is used as part of the pedaling, it's an e-bike.
If, however, you're controlling the motor action thru a mechanical throttle (twist grip or thumb lever seem to be the most popular), and pedaling is not necessary for forward motion, then it's a moped.
I work at a Honda/Yamaha/Can-Am dealership, and we see a number of the older style mopeds come thru the shop periodically. I've always been used to pedals on a moped being used for "light pedal assist" on hills. Aka, the small gasoline engine on the moped doesn't necessarily have the power sufficient to climb hills, thus the pedals. In Virginia, a moped is legally classified as a motor vehicle of 49cc or less, with a top speed of 35mph, must be titled, licensed, and the operator must wear a DOT-legal helmet and carry some form of picture ID on them while operating the vehicle. And the police will clock your speed. A slightly modified Honda Ruckus can easily outdo the 35mph limit on the flat - one of our salesmen got a speeding ticket for his a few years ago. Motor vehicle insurance is not required.
E-bikes in Virginia currently are treated as bicycles. No legal restrictions (although the rider is expected to follow traffic laws and local speed limits), no licensing, no helmets or ID necessary.
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Syke
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