After observing both Crewdson’s and Winogrand’s photographs, I carefully concluded which photo was the mirror and the window by using four points of comparison. At first I looked at the lighting for Winogrand’s photo which seems to be frontlit, compared to sidelit in the Crewdson’s. Along with the lighting both photos offer different types of texture, Winogrand’s being emphasized and Crewdson’s being more minimized. When observing focus and overall depth of field, I’d say both photos are sharp overall. Another aspect that both photos share coincidentally is a similar viewpoint, which is at eye-level.
When applied to the metaphor of mirrors and windows, I’d say that Winogrand’s photo is more of the mirror over the window because of the direct lighting and how emphasized our subject is in comparsion to Crewdson’s, which is more of a window or viewfinder peering into what life may be like somewhere else.
Szarkowski’s version of a mirror is that it reflects the photographer. Using this definition, then Crewdson’s Penitent Daughter, a scene directed by the photographer would be a mirror. Szarkowski’s version of a window is a view onto an objective world. Using this definition, the Winogrand photo is a window in that this photo shows a scene that he found and observed.
We will read other versions of the mirror that define the term differently. Closer to how you have in your post.