I've realized for a long time that the themes of WNMHGB and "Charlie X" are essentially similar - about a human being turning into an abusive monster when given supernormal powers. I've also felt that "Charlie X" was also very much like - and very probably inspired by - Jerome Bixby's "It's a Good Life", which became one of the most memorable episodes of the original "Twilight Zone".
There was some difference in the characterizations of Gary Mitchell and Charlie Evans. Gary Mitchell was a normal human who suddenly acquired exponentially increasing superpowers. This quickly mutated him into something beyond human, a being who no longer had any relationship with humanity.
Charlie, on the other hand, his lack of empathy and connection with fellow humans was not due to his psychokinetic powers, but with the fact that a lifetime spent in isolation had left him a self-centered personality who could not form normal relationships with other people, because such relationships had never been a part of his life before.
One thing to consider is that the two episodes were actually made a year apart from each other, when, in original airing they appeared back-to-back a week apart.