Generally, the words may be used interchangeably to refer to some amount or degree that is less than the whole. For example, you can say: She is partly responsible for their fighting. / She is partially responsible for their fighting. However, partially may imply favoritism because it is related to ‘partial’ and does have the archaic sense ‘in a biased manner’. To avoid ambiguity when describing favoritism, say: He is ‘partial’ to pizza. (Do not say: He was partially/partly favorable to pizza.)
What Is The Difference Between “Partly” And “Partially”?
