What's the difference between widgets and plugins for designers?

There are some widgets that are clearly more “widget-y” like an activity time tracker. Other than those, I’m having trouble understanding the differences between widgets and plug-ins for things like sticky notes. It seems like they essentially do the same things. Am I missing something here? Using sticky notes as an example, when should I use a widget one vs a plug-in one? Overall differences would be helpful too. Thanks!

You can read about some of the differences between widgets and plugins in the developer documentation: