Peculiar

Black holes and dark energy seem to have nothing to do with each other. According to general relativity, a black hole is a pure gravitational field so strong that its own energy sustains its existence. Such peculiar beasts are thought to emerge when massive stars collapse to an infinitesimal point, leaving just their gravitational fields behind. Supermassive black holes having millions or billions of times the mass of our Sun are believed to lurk in the hearts of galaxies.

In contrast, dark energy is a mysterious phenomenon that literally stretches space and is accelerating the expansion of the universe. Theorists think dark energy could represent some new sort of field in space, a bit like an electric field, or it could be a fundamental property of empty space itself.
—Science