Slim3 DI容器访问区别

$app->get('......',....)
$container=$this->getContainer();

Is there any difference between the following? Pimple docs uses the former while slim examples the latter. Is any of the two considered more formal in PSR terms?

    $server=$container['App\Model\Server'];

    $server=$container->get('App\Model\Server');

Slims Container implements the Interop/ContainerInterface, whereas Pimple does not. The Interop/ContainerInterface requires the container to have two methods: get()and has(). get() throws an exception (NotFoundException) when an entry is not found. With plain Pimple you only get a notice.