"No matter,all you have to work with is gravity
as THAT IS THE ONLY FORCE IN YOUR MODEL,so i
don't see why it makes a difference there
either."
[my emphasis] i can only read what you write even if you mean something different inside your head.
i think your electrician is talking about composition. he admits a distinction of orbit.
asteroids not only have different orbits, they also originate from different parts of the solar neighbourhood. typically, comets lose gas, water and dust as they pass by the sun. asteroids not so much. so it kinda seems reasonable to conclude that comets derive from an area in which water is more plentiful.
an object that usually takes the form of a dirty snowball with a tail is different in important ways from a body that usually takes the form of a dry rock.
having said that, the existence of water isn't limited to our own planet and the oort cloud. some asteroids have been observed with comet-like features. and some comets run out of gas.
at any rate, when examining a comet with a tail, then one ought to expect that it contains plenty of water, gas and dust. looking at wikipedia, the conclusion of the deep impact 1 experiment was that the comet's trail was informed by ice from the interior of the comet.
there was nothing in the result of the experiment that undermines traditional physics to my knowledge. they did learn a bit about the composition of that comet.
http://en.wikipedia.org/wiki/Deep_Impact_%28spacecraft%29