Classic vs Modern WebParts
The framework has pre-configured webparts to help minimize code so you only need to focus on the main application and not the configuration or data source. The webparts are pre-configured content/script editor webparts that are added/removed from a site collection’s webpart gallery.
The framework has modernized the classic webparts. The modern webpart has a similar approach, but utilizes the
configuration custom webpart property to store its JSON configuration data. The webpart configuration will automatically be updated to include a
Configuration button that will display the same modal form we have created for the classic webparts.