Language is unique because?

Researchers from Durham University explain that the uniquely expressive power of human language requires humans to create and use signals in a flexible way. They claim that his was only made possible by the evolution of particular psychological abilities, and thus explain why language is unique to humans.

Source: https://royalsociety.org/news/2013/language-unique-humans/

Languages can differ in many ways. They may use different sounds, they may make words in different ways, they may put words together to form a sentence in different ways, and that's just for starters! ... Dialects of a language may vary in terms of accents, the words people use, the way people structure their speech.

Source: https://lingroadshow.com/all-about-language/languages-of-the-world/how-can-languages-differ/