Zazen

Lots to say here, nearly everything is different and eye opening
Literally from the eye opening - in typically taught 'Hindu' meditation, eyes closed is the norm. Not the case with Zazen! Eyes must be only half-closed! You need to be aware of your environment - take in the sight, but reduce the stimulus.
Posture - erect spine, full lotus, on the floor VS curved spine, belly forward, full lotus only if possible, on a zabuton on top of a zafu
Focus: draw to the breath first, walking meditation
Mudra: cosmic vs gyan
Nearly everything about the methodology of meditation is different. Crazy how I have ignored the Zen traditional all this time and haven't realized how different it is.
Zazen - emphasis on incrementalism on every level from day 1 to mastery.
Focus point: right in front of you through half-open eyes VS third eye
Commonalities: group meditation as a power source