First of all, neither were suggested by Einstein. The concept of Dark matter comes from a Swiss physicist Fritz Zwicky from the early 1930s. He noticed that stars on galaxies’ periphery are rotating much faster than they should, so he guessed that there should be extra mass that’s somehow undetectable.
Dark energy concept is much younger, from 1990s. It was proposed by two astronomers trying to measure the rate at which expansion is slowing down, but discovered that it’s actually speeding up. Before that, it was believed that the universe got its initial speed kick from the Big Bang and is gradually slowing down. They won a Nobel prize for that too.
And Dark energy and Dark matter are wildly different and likely totally unrelated concepts. I think it’s unfortunate that they share the same adjective, it’s somewhat confusing. One is the expansion phenomenon, and the other is just another form of matter (most probably formed by a yet undiscovered field, quite similar to ordinary matter in a sense), but one that just doesn’t interact with ordinary matter or via electromagnetic forces. We “see” it through gravitational effects though. But there are currently no links between it and the expansion of the universe, and for now it doesn’t look like there’s going to be one.