Shaping is the term well established in behavior analysis and the term "free-shaping" seems to be an animal trainer invented term. Shaping involves reinforcement of successive approximations of a target behavior. It is a special kind of differential reinforcement. Both are compound procedures involving reinforcement and extinction, but while differential reinforcement changes only the rate or frequency (quantity) of a behavior, shaping changes the form (quality) of the behavior. They are both postcedent interventions in that they involve reinforcement and extinction, both postcedent behavior change processes. The antecedent conditions are not specified in the procedure.
The term free-shaping was conceived in order to provide a term for shaping wherein no contrived trainer provided prompts are utilized to evoke the approximations. There are occasions where one is operating under contingencies to avoid prompts and having to fade them and so it would seem there is a use for the term. There are reinforcers available for using the term. I am one of those people who dislikes all these new made up terms but free-shaping connotes something specific and useful and does not represent an error or misunderstanding of any kind. It is not conflating antecedent and postcedent interventions. Those who use the term can fully recognize what shaping is and is not. We can think of the "free-" part as specifying an antecedent intervention into the procedure and we put it with the word "shaping" because this addition is only for shaping projects.