Racially speaking not much of a difference. They both belong to the Indo-European group. But the major difference would be that Indo-Scthians were more of mlecchas according to the Vedic system in the past. There are two theories about the origins of Indo-Scythians. read more
Indo-Aryan peoples are a diverse Indo-European-speaking ethnolinguistic group of speakers of Indo-Aryan languages. There are over one billion native speakers of Indo-Aryan languages, most of them native to South Asia, where they form the majority. read more