Repository actually allows you to separate your business logic from database layer (Model).Repository/Entity are very common practice being used in Symfony Framework. Laravel introduces the Model classes as database layer and...
Category - Symfony
Looking forward to migrate Symfony 3.4 to 4 with Flex, here I found really well explained process. [Part 1/2] Migrating to Symfony 4.0 with Flex [Part 2/2] Migrating to Symfony 4.0 with Flex
If you are running Symfony 3.3 and want to migrate to Symfony 4 here I found really good tutorial, just follow the link.