It is a standard window wall, but the mullion caps are unually shallow, almost flush with the glass to give it a sleek look.
Curtain wall wouldn't be ideal or feasible for this design with all in and outs of the façade.
I think the grey spandel panel is there to create a consistant line across the building because of the louvred vent panels.
On Fashion House it doesn't have that which makes creates a unsightly jagged line on each floor, which is accentuated even more at night with the illuminated drapes. It looks terrible.