The difference between leftism and Trumpism is that, while both have sacred cows, those on the left are allowed to have a diversity of opinion, whilst the more strident far-left don't allow for much disagreement, mirroring the Trumpists.
The far-left is a fringe, while the more radical Trumpists are the entire Republican Party.
Dissent is not allowed in Trumpworld, you will bow down and obey Dear Leader. He is infallible.