Without any prior knowledge of the 2016 election, a viewer of this week’s two primary debates might reasonably be under the impression that the Democrats and Republicans aren’t running against each other, but rather for the leadership of two different countries. There are some issues that both parties are addressing, but the degree to which the Democrats and Republicans are often addressing entirely different problems is striking.

Sunday’s Democratic debate included an extended conversation on the connection between opioid abuse and rising rates of heroin addiction, as well as Wall Street regulation and climate change. These issues didn’t come up at all at Thursday’s GOP debate. The Republicans did discuss drugs back in September, but mostly focused on the question of legalizing marijuana. When climate change has come up in the Republican debates, it’s been mostly to ridicule the Obama administration’s focus on the issue, whereas Bernie Sanders stands by his argument that it’s America’s most pressing national security threat.

Topics that get heavy play in the Republican debate but are largely absent by the Democrats include economic competition from China, immigration, Benghazi, military spending, and “radical Islam”—both the phrase and the actual ideology. China and Benghazi did get some play in the very first Democratic debate back in October but mostly because Jim Webb was around to bring them up.

Yes, some of the selection of topics is in the hands of the debate moderators, but the moderators have tended to focus on the topics that have been most salient in the respective primaries. And when candidates have had opportunity to raise issues on their own, they’ve tended to choose ones of little interest to the other party. Hillary Clinton devoted her closing remarks tonight to the water crisis in Flint, Michigan. Martin O’Malley brought up Puerto Rico’s financial crisis.

Republicans, by contrast, tend to pivot whenever possible to terrorism and national security. Thursday night’s GOP debate began with a question to Ted Cruz about the Obama administration’s economic record, which he began by invoking “the sight of 10 American sailors on their knees, with their hands on their heads.”

It’s not just a matter of a domestic vs. foreign focus, though the Dems are much more focused on domestic policy and the GOP on terror. The Republicans are making the case that the world is, as Chris Christie puts it, “literally on fire.” For Democrats, the problem that needs addressed now is power—the concentration of wealth and privilege in the hands of the few. There’s not a whole lot of common ground between these two conversations and it will be fascinating to see which one dominates when these parties are finally forced to talk to each other later this year.

Read more of Slate’s coverage of the Democratic primary.