Is compacted snow the same as ice? I wouldn't have said so. To my mind the situation is basically this:
First we get undisturbed snow, which we can drive on reasonably well, so long as the depth isn't sufficient to stop us. When this has been driven on it becomes compacted but it still isn't particularly hard, so at this stage it will also have visible tyre tread marks, and these can give us a bit of extra grip, compared with what we encounter at the next stage.
The next stage is when this compacted snow has been driven on by more vehicles, such that the surface becomes harder and no longer shows tyre marks. In this condition the surface still looks white, and the increased hardness now affords us less grip, but I still don't call it ice.
The next stage is when this surface has had yet more traffic on it, with the result that the hardness increases further, and the surface has acquired more of a polished nature. This reduces the level of grip a good deal further, and things are now getting rather more difficult. By this time the surface will be looking grey in colour and the nice bright whiteness has gone. This is the stage at which I call it an icy surface, but I apprecaite others may apply that term earlier.
The final stage is where this hard polished icy surface acquires a film of water on top, and it is at this point that I feel it's time to park the car and crawl to somewhere safe on hands and knees. I kid you not: I've long been very nervous of walking on icy surfaces (it isn't just an age thing) and I have got even worse about this. Although some people find it amusing to see people falling on the ice and landing on their bum, it's not actually funny. At the very least they get a bad shaking, and there is always a risk of breaking something, especially in the case of an elderly person. Much earlier in my driving career I used to get irritated to find people walking on the road rather than on the pavement, but not any longer; I now understand their anxiety all too well.
Anyhow, getting back to driving, I don't mind fairly difficult conditions, but I would say this final stage surface is virtually impossible to cope with - unless somebody comes alomg and tells us that a good set of winter tyres will give us a sporting chance.
Maybe that's the case, maybe they will help us significantly, but otherwise I would call a halt at this point.
Best wishes all,
Dave.