Entanglement is the mystery of Quantum Mechanics. From a mathematical point of view, entanglement is associated with the non factorizability of quantum states, while its most striking physical consequence is non-locality. We show that entanglement is also deeply connected to the concept of distinguishability of quantum states. Two slightly different systems made of qubits can be more easily recognized to be different if the qubits are quantum correlated rather than classically correlated. This because entangled states can evolve faster under unitary transformations than classical states: Entanglement is high speed in the Hilbert space. This has important implications in technological applications like interferometry as well as in foundational problems as the quantum Zeno paradox.