Yes, the pilot used actual shots of different areas of Greystone for Collinwood.
(One thing we have to remember about the '91 DS is that the real reasons they used the model for many shots of Collinwood are twofold. One was because they extended the building with an entire wing that doesn't actually exist at Greystone - all the better to have closed off areas of the house.
And the other was that some of the trees on the property are so tall nowadays that it's impossible to shoot those areas of the exterior of the house because those trees are so close that they completely block it.)