[exe34]

Not quite. Dark matter is the hypothesis that the discrepancy between theory and observation is due to a form of matter that interacts gravitationally but not electromagnetically. So we can't see it, and thus "dark".

There are other competing ideas including a family of modified Newtonian dynamics models, but nothing comes as close as explaining the observations as dark matter does.

There was a paper recently that showed that the discrepancy may be the higher order terms from general relativity that is often neglected because they are believed to be small - but that idea still needs to be proven to work for a large variety of cases.

The observations in question for this Dark matter hypothesis include the rotation velocity of stars in galaxies and a few other things like gravitational lensing.

Dark energy is a different discrepancy with theory. It's a term that we have to add to Einstein's field equations to account for the observation that the universal expansion is accelerating instead of slowing down. Again there are competing hypotheses, like non uniform density on the largest scales, but nothing quite explains everything as dark energy.