Different node form id for add/edit
I'd rather say, added granularity is exactly what has been achieved by introducing entity form ID's specific to their entity type, bundle and operation.

You can now target the form for a specific entity type and bundle with a specific operation when using hook_form_FORM_ID_alter(). Before this you had to check the bundle yourself and also figure out whether the node already had an ID or not.

The form ID will be composed of entity type identifier, bundle, operation and the _form suffix. (Compare EntityForm::getFormID().)

If you require a more generic form alter for ALL node forms, you can use hook_form_BASE_FORM_ID_alter() which will be invoked with the base form ID that is ENTITYTYPE_form for entities, so node_form for content entities.

The invocation order along with a description of all three hooks is actually well documented in the description of hook_form_alter().