Re: And now, play the substitution game:
There are quite large differences between Corbyn and Trump, the most compelling being that Corbyn is (and has been for ~30 years) an elected politician, and now elected as the head of the Labour party. Trump has neither been elected to political office, or won the nomination of the GOP.
As for their effect on the political landscape, I'm fairly sure neither is changing the opposition parties viewpoint.
Trump is stating policies that are clearly fantastic and impossible to implement, but it's not like some of the other GOP aren't above suggesting that only christians should be allowed refugee status in the USA.