Pfalz is from the middle high German phal[en]ze, from the old high German phalanza, in turn from the medieval Latin palatia the plural of the Classical Latin palatium (palace), but construed as a first declension noun.

In other words, both "Palatinate" and "Pfalz" are Latinate names, and take their etymologies from the same word.

Could you elaborate on why you're interested in the Palatinate in particular? This is something every language does with the names of other nations. That's why the English name for Germany is Germany and not Deutschland, even though the two names are incredibly different - the Latin name for the region was Germania.