The major difference seems to be that preact uses native browser events, unlike react which implements "synthetic events" - so preact may have issues in old bro

The major difference seems to be that preact uses native browser events, unlike react which implements "synthetic events" - so preact may have issues in old browsers like IE8 (https://preactjs.com/about/project-goals/ https://preactjs.com/about/project-goals/)