same difference

Blend of same (thing) +‎ (no) difference, which incidentally continues to make logical sense.

• Audio (General Australian):

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same difference

1. (idiomatic) A distinction which makes no difference; a distinction which does not matter.

   Synonym: distinction without a difference

   • 2011, Constance Briscoe, The Accused, →ISBN, page 274:

     "When you say she was a tart, do you mean a whore?"
     "It's the same difference," Betty said.

• Often used in a grammatically incomplete form, as a pro-sentence, meaning "That is a distinction which makes no significant difference." For example:

2000 July 31, Lev Grossman, “Report From MacWorld Expo”, in Time:

Apple as a company has been as much about design as about technology. Is it in danger of putting form ahead of function? Same difference, says Jobs.