The difference between Republicans and conservatives used to be minimal. I'd say that conservatism swung so far right that most long term Republicans didn't even realize it. The vast majority of people who vote Republican or Democrat do so nearly without any understanding of a particular candidate's positions apart from the general party platforms and only votes on one or two issues that are personally important to themselves. With how gerrymandered the country is, especially in many Republican controlled states, the middle ground for centrists Republican and Democratic candidates is gone.

This was started by a concerted effort in the 1980s to turn the country more conservative, which was very successful and backlash to the liberal culture expansion of the 1960s through the 1970s. I don't however believe that the architects of that plan foresaw the damage that would come from polarization.

America has a large reckoning coming as we must learn and define what we want our national image to be. It's certainly no longer the shining city on the rock. We're far closer to the loud, obnoxious uncle at the dinner table talking about what we did in the past. Unless we can find common ground as a country, we're destined to fade in global power far quicker than we should have.

Edit: Typo