This study aimed to investigate the phenomenon of diminutive morphological function in terms of productivity, similarities, and differences in inflectional bound morphemes between English and Pashto, particularly in the categories of nouns and adjectives. The study also aims to examine the possible influence of ancient languages, such as Greek, on the diminutive morphological function and productivity of these two languages. It is generally assumed that languages descending from similar parental groups share the same diminutive function and productivity pattern in marking morphological mechanisms such as number, gender, and case. Different online sources, libraries, and publication papers were consulted to make a comparison between these two varieties. The findings revealed that both English and Pashto retain a morphological function, but English uses limited inflectional morphemes. Pashto, on the other hand, employs a wide range of suffixations, particularly in marking the diminutive aspect, and that differentiates it from English in semantic and pragmatic expressions. The findings aligned with the initial hypothesis developed that languages descending from similar parental groups use a similar pattern of morphological mechanisms. The only difference is that English drops the inflections to a greater extent because it underwent different phases of modifications, while Pashto still retains the inflections and, in turn, reveals greater productivity. Moreover, the findings disclosed that Pashto is closer to Greek in its inflectional nature and functioning of diminutives than English.