Comparing the Magician in RMSS to the main RMFRP book, the differences are that Magic Ritual and Spell Mastery are not listed as Everyman Skills in RMFRP, and Channeling is no longer listed as restricted skill in RMFRP.
Under Profession Bonuses, Power Awareness is now +20 instead of +10 and Power Manipulation has been removed. (was +10, skill is not in RMFRP)
Now, when I go and check the Magician in RMFRP Spell Law of Essence, all those changes have been reversed, Spell Mastery and Magic Ritual have been added back into the list of Everyman skills, Channeling is listed as a Restricted skill and under Profession Bonuses Power Awareness is back to being +10 and Power Manipulation has been put back at +10, making it identical to the RMSS Magician again.