There was a significantly higher (p < 0.001) total time spent in moderate-to-vigorous physical activity (51.2 ± 3.1 vs. 32.6 ± 5.9 min), total energy expenditure (411 ± 66 vs. 210 ± 46 kcal), and total step count (6773 ± 556 vs. 4108 ± 781 step) during Zumba fitness when compared to salsa dance. Significant pre-to post-class improvements in positive well-being (p < 0.01, partial η2 = 0.41) and psychological distress (p < 0.001, partial η2 = 0.72) were simultaneously observed for both salsa dance and Zumba fitness.I don't know enough about the kind of salsa classes in the study to speak knowledgably, but since this is the internet, I won't let that stop me:
My guess is salsa is a little more connected to recreation than Zumba, which began when an exercise teacher had to improvise with his Latin dance tapes, so Zumba is a bit more focused on physical fitness. But "a bit more" is important in that sentence: Zumba only works if you focus on the same thing you should focus on with salsa: having fun moving.