What's the difference between a Component and a Model in Craft 3? I'm trying to familiarize myself with the Craft architecture and I can't understand whether I should be extending craft\base\Component or craft\base\Model for my business logic models. Component seems like a pretty lean class that only adds a few initialization events to Model.
Models  are classes that contains abstractions of the reality, for example you could have the model car that contains the technical information about it, how many wheels it has and it's brand. Models are usually not supposed to contain any logic. So it's just a "container" with information 

Components are more like services that contains business logic to work with your models, for example the service car would handle the logic to let your car model drive and move and such. Components in Yii2 are mostly (not always) treated as singletons while you want to have many different instances of your models