The main difference between a puffy taco and a chalupa lies in the shell. A puffy taco is made with a light, airy, and puffed-up shell created by frying masa dough. In contrast, a chalupa typically has a thicker, chewier shell, also made from masa dough but shaped more like a small boat and less puffed. Chalupas are often fried to a golden crisp but retain a chewy texture, unlike the crispiness of puffy tacos.