Yep. There's a difference between a 2-5-1 and a substition for a 2-5-1, one being that they won't sound the same, and the other consisting of different notes. It's like be having a substitution for a Rolex. It may look like a Rolex, but if it said "Folex" you'd still understand it was SUPPOSE to be a Rolex, and you can wear it like a Rolex, but everyone will know the difference once they looked at it closely.
