If vegetables are crinkle-cut, they have been sliced into long pieces with gentle waves along the edges, not straight smooth sides. You see this most often with potatoes: crinkle-cut chips (in American English, crinkle-cut fries) have ridges you can see and feel. Carrots and other vegetables can be crinkle-cut too, usually with a special wavy blade. The waves are for looks and for a bit more crunch; the food is still the same plant. It is a friendly cooking and food-packet word. You would not use it in a serious report about farming. Though actually the hyphen matters: it is the cut that is crinkled, not a vegetable called a “crinkle.”