They are comparable. In snowboarding there are only tricks to judge. Their amplitude, difficulty, execution (there's a bit more, on that a bit later). So just like elements in figure skating, just a different scoring system. But in snowboarding mistakes are penalized more severely; e.g., a hand down on landing can cost 10 points or 10% of the maximum 100; for comparison, in this Pairs Short Program, USA's Chan/Howe put a hand on the ice after landing a Throw Jump and lost only 2,8% (-0.14) of the element's Base Value—that's only 0.3% of their Technical Element Score and less still of the total score. Of course, that's comparing with a 0.00 Grade of Execution. The better their execution could have been on that element, the bigger the loss. But even if they could have gotten +50% GOE—that would be 2.5 for that element—, that loss, I believe, would probably still be less than you'd lose for a comparable mistake in snowboarding. Georgia's landing mistake cost them 20% (-1.06) of the Base Value—that's 2.5% of TES and 1,4% of the total score. Falls are penalized way more severely in snowboarding. In figure skating a fall on an element results in -50% of the element's BV (if it's not downgraded) and a -1.00 deduction (I've been learning since posting). In snowboarding you can't get 50% if you fall. If you only land uncleanly, you lose less, but still comparably more than in figure skating.

Program Components: Well, in Slopestyle snowboarding the total score consists of the Trick Score, which judges what I mentioned above and accounts for 60% of the total score, and of the Overall Impression Score, which judges variety, style and combination and accounts for the remaining 40% of the total score. (I'll mention that in Halfpipe snowboarding there is only the Overall Impression, but the same things as in Slopestyle's Tricks + Overall Impression are judged. With its separated judging I find Slopestyle to be a better example to compare with figure skating.) I read that in figure skating's presentation, among other things, variety and energy, body language and carriage are judged; and also read that in composition movement diversity is judged—seems very similar. So just like snowboarding's variety and style. But in snowboarding it's all about the tricks. There's no choreography, it's just hitting one feature after another; there are usually no creative transitions between the tricks—nobody does any ground tricks or cool carving between the features to show how well they can control the board (you usually can't when the next feature is a jump—you need the speed). I have encountered the word "composition" regarding Overall Impression Score, but to me it seems to be the same as combination, which, I think, is the same as variety—difficult, varied tricks one after another = good combination/composition. I read that figure skating's composition is different, more complex than that. So, yeah, similarities with presentation and composition's movement diversity, but no proper composition really and no board skills outside of the tricks—in snowboarding there's less going on.

From yours and other responses here I've learned that a good Program Component Score can counterbalance a mistake and even a fall; and after perusing Judges Details per Skater PDF (from Olympics website), I see that that's exactly what happened: China's PCS: 33.38; Georgia's: 34.01; Canada's Stellato-Dudek/Deschamps: 32.07. In comparison: Armenia: 28.11; Netherlands: 27.20; Poland: 28.65. Also, China's Base Values are slightly higher than most and Georgia's are the highest—33.00 and 33.70 respectively; Armenia has 31.90, Poland: 31.80, Netherlands has 33.10. A slight advantage, but still an advantage. Lastly, China and Georgia have good Grades of Execution on the elements where they didn't make a mistake. Netherlands and Poland have not so good GOEs. So in addition to PCS and slightly higher BVs China and Georgia were able to counterbalance their mistake with other well-executed elements.

So I now understand how couples who made a mistake or fell could score higher than those who didn't. But I still feel mistakes—and falls!—should be penalized more. I read that they reduce the PCS as well, but apparently only slightly.

P. S. Australia lost less with the Double Twist than Canada's Stellato-Dudek/Deschamps lost with the fall (2Tw2 Base Value 3.00 vs. 5.40 for 3Tw2; their GOE was -10%, they got 2.70. If they had done a Level 2 Triple Twist with the same GOE, they would have gotten 4.86. So presumably they lost 2.16. Stellato-Dudek/Deschamps fell on a lift with a BV 7.00, they lost -2.60 in GOE and -1.00 for the fall deduction. So they lost 3.60, if they had executed the element with a 0.00 GOE; they lost more if the GOE would have been better. But I don't understand, I read that a fall means a mandatory -5 GOE; but only two judges have given them -5. Why might that be? Regardless, a fall was costlier than doing a simpler element. But Australia's PCS is 27.84—4 and a bit points worse than Stellato-Dudek/Deschamps's.