It sounds to me that iron “fist” is external, and iron “palm” is internal. Is there an internal way to do iron “fist”? Is there an external way of doing iron “palm”? Are punches used with chi considered an internal iron “fist”?
Both can be either internal or external. The word internal /external has to do with the training aspect of anything not the type of movement or hand postition.
The internal training would consist of static postures breathing and forms etc etc. The external would be striking and conditioning the hand etc etc.