No, I don't think there is much fundamental difference. Some RSS readers support inbound emails as a feed source and I get my RSS feeds delivered via email. I t

No, I don't think there is much fundamental difference. Some RSS readers support inbound emails as a feed source and I get my RSS feeds delivered via email. I think the main reason newsletters are "winning" over RSS right now is that everyone has an email address but not everyone has a feed reader configured. It provides an easy onboarding where you can start getting it in your inbox available on all of your devices and once that becomes annoying you can easily set up filters to organize.