There used to be a distinction in the US: Saran Wrap was made of Saran and was much less oxygen-permeable than other cling films as a result. In a development that represents some kind of evidence about trademark law, Saran Wrap in the US is no longer made of Saran, due to concerns about plasticizers leaching into food; but it is still sold as "Saran Wrap". Here in Argentina, I can still get cling film made of PVDC, just not Saran-brand PVDC.