Steel housing & bigger fllters are what distinguished the domestic from the professional engines.
Blade brakes are forced on the factory due to idiots with very good lawyers, nothing to do with consumer demand .
You would not believe how many people ask me if I can remove them .
Commercial mowers are always a lot heavier than domestics as they are designed to be used a lot more hours in rougher conditions and bouncing around in trailers & trucks,
Funny enough the bulk of my commercial customers are now using domestic mowers because the commercial have now gotten too heavy .
AS for the catchers, they also fit 2 pr of high lift blades to pack more the grass into the catchers and that rips the rear wheels which tend to last a single season.