A store keeps or accumulates (something) for future use.
A pantry is a small room or large cupboard in a house, usually near the kitchen, where food is kept.
The goal of a designer is to listen, observe, understand, sympathize, empathize, synthesize, and glean insights that enable him or her to make the invisible visible.Andrew Grove
The above meanings say it all they are both used for storing items or food stuffs. The pantry is a regularly visited to room or cupboard when food is needed urgently in a kitchen. The store is where the bulk of food is stored for economic purpose and will be needed when in the future.
A pantry can also be designed in different ways; some designers actually spend time designing a pantry. You can have a small cupboard in your kitchen for a pantry if the architects did not make room for one for you.
In conclusion a pantry is a store with a small storage capacity.