Side zipper should be a tab zipper, also called easy tear zipper.
Tab zipper is so easy to tear and open, also it can keep the bag complete after tearing and opening, so it will not break the design on the bag.
But for inner zipper, the bag top has to be tear off when the consumers want open the bag.

For flat bottom pouches, tab zipper provides 2 types for the top open, normal and big opening, but inner zipper is only available for normal opening.

The difference between side zippers and inner zippers in the opening mechanism. For example, many customers choose side zippers for coffee packaging because they offer a better user experience, give the product a more premium feel, and make the bag more aesthetically pleasing. Also, the opening of a side zipper is smaller than that of an inner zipper.

The inner zipper is completely hidden in the bag mouth, the appearance is flat, and the tab zipper pull tab is prominent, making it easier to identify visually.

The cost of the inner zipper is lower than that of the tab zipper.