In dedicated environments where you have multiple nodes the deploy hook only runs once, while the pre_start hook (which is specific to dedicated gen 2) is executed on all nodes.
$PLATFORM_REGISTRY_NUMBER is an environment variable that is only present on dedicated generation 2 clusters (but not on grid nor on dedicated generation 3)
In dedicated environments where you have multiple nodes the deploy hook only runs once, while the pre_start hook (which is specific to dedicated gen 2) is executed on all nodes.
$PLATFORM_REGISTRY_NUMBERis an environment variable that is only present on dedicated generation 2 clusters (but not on grid nor on dedicated generation 3)