There are more differences in the type systems. I am sure you know Haskell compiles to [System FC](https://downloads.haskell.org/~ghc/7.6.3/docs/html/users_guide/an-external-representation-for-the-ghc-core-language-for-ghc-6.10.html). In terms of Barendregt's [Lambda cube](https://en.wikipedia.org/wiki/Lambda_cube) this means that Haskell is more akin to \$$\lambda 2\$$. As far as I can tell your semantics are like \$$\lambda \to\$$ and are therefore simpler.