As mentioned above, it must be the seat height. Apart from internal strengthening in the main and tail planes and the roof windows, the structure is identical. Oh yes, the Reims built C150 version had an O-240 130hp engine which did wonders for the climb rate : ok:
Those roof windows usually make the cockpit feel more spacious due to the extra light rather than more cramped.
Not the most capable aerobatic mount on the planet but loads of fun and "cheap" to run.