The poskim I’ve seen assume they’re the same parameters.
Which Shittos (by that I mean Rishonim or earlier Achronim, not modern day Rabbonim) have said that they are the same? Rav Moshe is very careful to say they are different, when he discusses the Aruch Hashulchan you mentioned.
???”? makes a distinction between ??? (always ????) and other areas (e.g. hands, face) which are ???? in ???? ?????.
1: That discusses Kriyas Shema.
2: That exact Rashba is used as a source for the Mattirm (for Kriyas Shema), as he brings in the concept of “Ragil Bahen” being Muttar. Therefore (the argument goes) anything that is Ragil does not create Hirhur, and hence Muttar to read Kriyas Shema before it (note the Rashba L’Shittaso against the Rosh l’gabei the din of an absolute Ervah except Oso makom).