The slimmer adapter is over 250 g lighter without impacting the overall performance of the laptop. Users can also now recharge the laptop via USB-C whereas that was not possible on the older G532 series.
https://www.notebookcheck.net/Asus-ROG-Strix-Scar-15-G533-ships-with-a-smaller-240-W-AC-adapter-compared-to-the-280-W-adapter-for-the-G532-series.552080.0.html