SE and SER sliding windows place the opening in different parts of the window. Compare that layout with the bed, seating and cabinetry around the proposed installation.
Do not choose from a claim about highway airflow alone. Air movement depends on the whole vehicle and conditions; follow the window and vehicle operating instructions and assess the layout primarily for its intended use.
The practical difference is opening placement
In the SE and SER models discussed here, the screened opening is positioned toward the front or rear of the window. That changes where you reach the slider and where an opening sits beside a bed, seat or cabinet.
Compare photos of the exact left- or right-side model. A series name by itself does not identify every dimension, screen arrangement or vehicle application.
Plan airflow as a whole-vehicle system
Air movement depends on wind, vehicle shape, other openings and any powered ventilation. The position of one window opening does not guarantee a specific intake or exhaust effect.
Choose and operate the window according to its instructions and the vehicle requirements. Do not treat a general description of pressure zones as advice to drive with a particular opening configuration.
Choose from the interior outward
Check which part of the window you can reach, where the screen moves and whether furnishings would block operation. Compare that practical access with the other windows and vents in the build.