After looking over all the evidence at hand, I had come to the conclusion that the "red" depot was in fact the original, but I could not account for the "snow" depot at all. Here is what I came up with....
Look at the part of the station in the vintage view I have highlighted here. 
And then look at the part of the structure in question I have highlighted here.
Now I ask you.... if this is not the same structure, albeit highly altered- WHY would they have made an overhang like that? And why construct it with a buttress just like the one in the vintage postcard view? (Not sure if buttress is the right word. The "support member going from the wall to the roof" then. Why make the overhang on one side only? Doesn't make sense. I say this is the same building with two additions, an added window, added stairway to the second floor, etc. etc.---- AND the roof foreshortened on 3 sides. The roof remains the same only on the side I have highlighted.
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So this is where we stood on the mystery.....I said it WAS the original depot, albeit highly modified. Alan said it wasn't. And although he was far more correct than I- we were BOTH wrong! But in a way we were both RIGHT.