Chalupas and tostadas are similar in that they both top a crispy fried tortilla with taco toppings like lettuce, tomatoes, and cheese, but the difference between the two comes down to the shape of the tortilla shell. Tostadas are traditionally flat, while chalupas are served in a shallow “bowl-like” shell. In Mexico, the chalupa tortilla is almost always thin and crispy, but in the United States chalupas are popular in thicker, softly crisped flour tortillas. These thicker tortillas look like a bigger version of Mexican sopes or Navajo fry bread.