Don't these look very similar?
http://htmlemail.io/img/preview-plain.jpg
http://mailgun.github.io/transactional-email-templates/actio...
http://htmlemail.io/img/preview-plain.jpg
http://mailgun.github.io/transactional-email-templates/actio...
There are several differences with the templates for sale on HTMLemail.io: More layouts, a 6 column grid, better responsive support for mobile (including Gmail apps), includes high resolution image assets for social media and app store buttons, better support across all clients including Gmail and Outlook.