Many who think of themselves as being on the left will sometimes make a significant distinction between the right (or center right) and the far right. While this is not necessarily strictly tied to political party, to simplify things overall it appears that the Democrats could be characterized as right-wing, moderate conservatives and the Republicans tend to be far-right, ultra-conservatives; there is a shrinking moderate faction of the Republican party, however.
The difference between the right and the far right is simply this: The far right believes its own bullshit. A right-winger will lie and connive and not necessarily believe everything he or she says in order to get their way, but a far right-winger is fucking crazy. They actually do believe things like Americans are God’s chosen people, black people are genetically inferior and that climate change is a hoax.
There is the mistaken notion, in my opinion, that a far right-winger or ultra-conservative is worse than just a center right type. They both do the same bad things and so I believe they are equally bad, but the far right person or leader you can see coming from a mile away, while the simply right-wing guy (or gal) can sneak up on you if you are not wary and do more damage and possibly get away with it for much longer before being discovered.