Raw makhana is the plain dried seed after popping. Roasted makhana has been heated until crisp and is ready to eat. Both are the same seed; the difference is the last step.
Raw makhana
Soft and slightly chewy straight from the pouch, with a neutral taste. It is an ingredient rather than a snack — used for kheer, curries, roasting at home in ghee, or grinding into flour as a thickener. It keeps longer because there is no added oil to go rancid.
Roasted makhana
Crisp, nutty and ready to eat. Roasting drives off residual moisture, which is what produces the crunch. Once roasted it should be kept sealed — makhana pulls moisture from the air quickly and goes soft.
Does roasting change the nutrition?
Not materially. Roasting removes water, so figures per 100g shift slightly upward simply because there is less water in the same weight. Protein and fibre are not destroyed by dry roasting. What does change nutrition is what gets added — oil, salt, seasoning.
Which should you buy?
Buy roasted if you want to open a pouch and eat. Buy raw if you cook, or if you like roasting it yourself with your own ghee and salt — many households prefer that, and it is cheaper per gram.