Do we observe different events or activities on main-belt comets, or do they behave exactly the same as regular comets?
(Apart from the obvious difference in orbit size/shape.)
The Wikipedia article for main-belt comets currently states the following:
"The Jet Propulsion Laboratory defines a main-belt asteroid as an asteroid with a semi-major axis (average distance from the Sun) of more than 2 AU but less than 3.2 AU, and a perihelion (closest approach distance to the Sun) of no less than 1.6 AU."
(So this appears to denote the main asteroid belt, not the Kuiper belt or the Oort cloud.)
"David Jewitt from UCLA points out that [main-belt comets] are most likely not comets with sublimating ice, but asteroids that exhibit dust activity, and hence he and others started calling these class of objects active asteroids."
(The article cites this video, from the official HST channel, as the source for this quote.)
If "active asteroids" behave exactly like comets, with no measurable difference in observation, how can he claim the two types of objects are likely composed of different materials, and operate with different mechanics?
What is the scientific basis for this differentiation?