I have a very subjective comparison of SC and ED ships in my head. I have ED (obviously) and I tried SC with a friend who backs it. He has an Aurora I think (with the circular hatch on its side) but he stole a constellation from someone upon my request and I managed to fly two SC ships this way.
My very personal observation is this, and I don't know if something like this can ever be objective...
In ED, ships fly and feel as you'd expect from their size, and you absolutely feel their momentum. Both with flight assist on and off, it's a lot easier to stop a small and light ship compared to a large and heavy ship. The flight model is designed to make sure you feel that you are in a spaceship equipped with thrusters pointing to major directions and it's the thrust applied by those thrusters which makes you move. You even feel which side thrusters are stronger than other because they are obviously not equal in strength. For example, Asp's top side thrusters are a lot weaker than its downside thrusters, therefore if you accelerate to top speed forward, then pitch so either your top or bottom is pointing to your movement vector and apply thrust in the opposite direction, downside (bottom of the ship) thrusters will slow down and stop the ship a lot faster than the topside thrusters. Try it if you like.
In SC, there wasn't much of a difference between the feeling of the ships as they accelerated almost exactly the same, in any of the movement axes. I think I felt the bigger one was a little slower on the top speed (and maybe the acceleration too) but it was definitely not drastic a difference as you would get in ED. Other than that, the ships stop almost immediately where you zero throttle, taking away most of the feeling of momentum. You don't get the drift you get if you zero throttle or even reverse when going fast and the ship (I'm looking at you conda) just refuses to stop (and you bump harmlessly into the control tower of the landing pad). I would describe the feeling of the flight as a manned turret glued to the top of a giant hockey puck with a glued bottom on a grass lawn. Yes, I thought really hard to think up this imagery. Also, you somehow don't feel like thrusters are pushing you but as if some invisible tractor beam is pulling you in the direction you want to go. I don't know why I got that feeling, probably the acceleration curves.
Stealing the constellation was really enjoyable though, I'll give them that. We basically talked to someone who has a constellation and he (I assume) invited my friend on board. We took off and I asked, pretty innocently too, what happens if we kill the pilot. I didn't think he would up and shoot the guy in the face.
Went something like this:
Hey <friend>, what happens if we kill him, do we explode with the ship?
-I dunno, let's see!
***gun noises***
-I guess we have a connie now.