Looking carefully at the images, we notice that there are five differences among the pictures:
From here, we notice that all twenty-six letters are given, and that each one of them is given by a different combination of these five differences. (For example, P has a downward-tilted straw, reads “CHIPS”, has the starburst with a large downward point in the center, and lacks both the extra line and the extra kernel on the bag of popcorn.)
However, the center line of unlettered pictures is not unique. Each of these has the same set as one of the letters. The top one has a downward-tilted straw, reads “CHIPS”, has the starburst with a large downward point in the center, and lacks both the extra line and the extra kernel on the bag of popcorn, just like the P we just described, so the first letter is P. We can continue this for all seven pictures, matching them to their lettered counterparts, to get the answer PRETZEL.