The difference is in the front panel: The Selfie Booth has a white Perspex cover. Perspex is a solid white clear plastic that is the material used for the cover. The Mirror Booth has a bespoke two-way mirror cover. When you get the Selfie Booth package, it does not come with Mirror cover. The Selfie Mirror Booth, however, comes with both Perspex and mirror covers.
You can also buy the Selfie Booth now and buy the Mirror Cover separately later.