These seem likely different concepts to me. Apostrophe is a nice looking markdown editor. Ensō is a minimalist writing tool (I hesitate to call it an 'editor')

These seem likely different concepts to me. Apostrophe is a nice looking markdown editor. Ensō is a minimalist writing tool (I hesitate to call it an 'editor') designed to facilitate a certain kind of writing by hiding text that has already been written and preventing the user from editing it. The focus here seems to be getting the writer to just get the words out and then use a (presumably) different tool to format and edit later.