flax meal = ground flax seeds (flaxseed). You might also see some pre-ground flax seeds called "milled" flax.

Basically all the same thing .. whole flax seeds that have been ground up . I think flax meal tends to be a bit coarser, whereas milled flax is more finely ground. Personal preference, I guess. I prefer to buy whole seeds and grind them at home (cheaper). Also, whole seeds have a longer shelf life ... once ground, they have to be kept tightly wrapped in the fridge and used up fairly quickly.