It's hard to point to a particular "language feature" because all the differences stem from the differing evaluation strategy. Any given feature on its own may

It's hard to point to a particular "language feature" because all the differences stem from the differing evaluation strategy. Any given feature on its own may be interesting, but you can always come up with some alternative approach/representation/encoding/whatever in $YOUR_FAVORITE_LANGUAGE to diminish the feature's value. You really do need to understand term rewriting to understand the language. There are, however, lots of interesting things that most other languages don't have. For example, extremely powerful pattern matching: https://reference.wolfram.com/language/guide/Patterns.html https://reference.wolfram.com/language/guide/Patterns.html And a form of predicate dispatch: https://reference.wolfram.com/language/tutorial/TheOrderingOfDefinitions.html https://reference.wolfram.com/language/tutorial/TheOrderingO... Or a universal data representation: http://reference.wolfram.com/language/ref/FullForm.html http://reference.wolfram.com/language/ref/FullForm.html Or the ability to extend the syntax by adding to a 2D operator precedence parser's dispatch tables: http://reference.wolfram.com/language/Notation/tutorial/NotationSymbolizeAndInfixNotation.html http://reference.wolfram.com/language/Notation/tutorial/Nota... This is all to say nothing of the standard library, but beyond evaluation strategy, what parts are "library" and what parts are "language" is so blurry as to be practically meaningless.