Differentiable vs Diffeomorphism - What's the difference?

As an adjective differentiable

is (calculus|not comparable) having a derivative, said of a function whose domain and codomain are manifolds.

(mathematics) a differentiable homeomorphism (with differentiable inverse) between differentiable manifolds.

(wikipedia differentiable)

(more)

(calculus, not comparable) Having a derivative, said of a function whose domain and codomain are manifolds.

(comparable, of multiple items) able to be differentiated, e.g. because they appear different

(en noun)

(mathematics) A differentiable homeomorphism (with differentiable inverse) between differentiable manifolds.

* (wikipedia "diffeomorphism")