The school I train with has a fantastic article that explains this clearly. Here is an excerpt:

“Consider this classroom scenario…

You’re teaching your students a social-emotional learning (SEL) lesson about conflict-resolution, and students are engaging in role plays where they identify how they are feeling and practice working out a conflict. Then they head out to recess, and immediately are fighting over who gets to go first on the swings.

When your students are back in the classroom, you ask them, “I’m wondering why we didn’t use our conflict resolution skills we’d just been practicing to solve that problem?”

Blank looks. Shrugs. A student finally offers, “I was just super mad. I couldn’t think straight.”

Does that sound familiar?

For our students to access a sense of calm, in addition to their problem-solving skills, when they are in an argument on the playground, they need to have first practiced finding regulation when their system is more relaxed and at ease.

This is why mindfulness and social-emotional learning (SEL) programs can be a powerful component of your school curriculum and culture.”

You can read the full article here: https://www.mindfulschools.org/what-is-mindfulness-and-social-emotional-learning/

“When taught together, mindfulness and SEL can have a powerful affect on students’ ability to manage emotions and demonstrate social and emotional aptitude. This in turn leads to improved behavior and academic outcomes.” ~ Aperture Education, How Mindfulness Fits into the SEL framework

“Both SEL and mindfulness each have their limitations. Being mindful doesn’t ensure a student can successfully build relationships with their teachers. Having social and emotional skills can’t guarantee a student can mentally ground themselves if they face a challenging situation. Fortunately, they can be taught together to ensure students benefit from a well rounded education.” ~ Edulastic, Mindfulness vs Social Emotional Learning: What’s the Difference?