Flex feels like a lower level of abstraction. You provide a docker file and what you want your machines to look like (vcpu, ram, storage) and it handles everyth

Flex feels like a lower level of abstraction. You provide a docker file and what you want your machines to look like (vcpu, ram, storage) and it handles everything else. Standard is much closer to Heroku with the added benefit of being able to call APIs for managed services. If you want control over your environment (including what dependencies are available), you want to use Flex. In every other case, I think Standard is the way to go.