The Hopper does not up-convert so you are getting the same picture resolution as the Hopper 2 receiver, that is 480I, 720P or 1080I depending on what the channel is displaying. You can't set it to send only 1080P for example. There are usually a few PPV movies that can be ordered with 1080P and then the receiver will send a 1080P signal otherwise there is no 4K or 1080P channels that DISH has. Depending on what 4K TV someone has the picture from the Hopper 3 could look better on a 1080P TV than a 4K TV until there is 4K material. That's because the TV does the up-converting to 4K and some TV's do a better job than others.
If you had a 4K TV and used the 4K Netflix app on the Hopper then the Hopper 3 would display a better picture on a 4K TV than a Hopper 2 could.