As verbs the difference between blither and blether

is that blither is to talk foolishly; to blather while blether is {{cx|especially|northern England|Scotland|Northern Ireland|lang=en}} an alternative spelling of lang=en.

As an adjective blither

is comparative of blithe.

As a noun blether is

{{cx|especially|northern England|Scotland|Northern Ireland|lang=en}} an alternative spelling of lang=en.