Thanks, I think! It looks like the vent is permanently open, so the rainfly is effectively a small umbrella which covers it (attached how?). I assume the weight difference between the two variants is due to lighter weight fabric in both the rain fly/umbrella and the vestibule section of the tent.
My past experience with single wall tents has been that the seams always leak if it rains, so I wonder if this one is any different. At least the multiple vents should reduce condensation.