| The background and planes and helos are all "photo-realistic".
`photo realistic' is overrated with respect to the current batch of R/C flight simulators.
As for the plane, all (most?) of the modern commercial simulators allow you to see the control surfaces move -- which is very nice. You can also put `textures' (basically pictures) on the plane's surfaces which basically makes it look more realistic. Displaying objects like this in 3D games (with 3D hardware) has been `the norm' for several years now, and most (all?) of the current commercial simulators do this for your plane.
As for the scenery, several of the simulators give you flying fields based on actual pictures taken there. RFG3 calls this `PhotoField'. It's very pretty, but it's also rather limiting.
For starters, you can't even move. Since the pictures were all taken from one location, you need to be sitting at that one location and can't leave it.
Another problem is that you can't really `collide' with an unmoving picture that's right in front of your face, so there has to be a 3D world kept track of by the simulator in addition to that picture. The problem is that this 3D world doesn't always match up perfectly with the picture, or is very simplistic -- like a bunch of trees will be modeled internally as a simple wall (sometimes going all the way up too. I seem to recall crashing into the edge of the world in XTR several times!)
One advantage of this `picture scenery' is that it doesn't require much CPU power to display -- and yet it looks really good.
The alternative is having the simulator model and display each object individually. With modern computers and graphics hardware, this works out really well -- it doesn't look quite as good as the photo-based scenery, but it's really close. And more importantly, it's more functional -- you can walk around, even get the view from inside your plane. And collision detection is usually much better, since the model used for collisions matches the model used for viewing exactly, since they're the same model.
Also, that allows you to do things like edit the actual scenery -- you can add objects, perhaps change the weather (clouds, possibly rain?)
-- stuff you can't do if your scenery is simply a bunch of pictures with a blocky 3D model behind it.
| You can modify the planes' characteristics also, to make them fly | just like your real model.
Well, you can try :) (Though really, the current crop of simulators all have pretty good physics, and the planes fly reasonably realistically.)