Expressiveness
Supporters of Interlingua note that their language not only conserves the natural aspect of Western languages, but also their rich, subtle treasury of meanings. Interlingua flows regularly from its Romance, Germanic, and Slavic source languages, and thus it possesses their expressiveness.
Esperanto supporters contend that, by its liberal use of affixes and its flexible word-order, is equally as expressive as Interlingua or indeed any natural language, but is more internationally neutral. While acknowledging that Esperanto is a product of rational construction, not historical evolution, they argue that, after the prolonged usage of more than 100 years, it too has become a living human language.
Read more about this topic: Comparison Between Esperanto And Interlingua