Why does store mean shop?

So, I noticed that store means:

• A store (shop)
• To store (items; save up)
• To store (stocking up)

Meanwhile, storage means:

• preserving or safekeeping things,
• the act of storing things, or
• a place where things are stored

For example:

• Food storage is important in the Arctic region.
• Cloud storage is useful for store files online.
• Our shop needs more storage space.

So, as I understand it, storage can be analyzed as:

• store (keep things), plus
• -age (a suffix to indicate a state, place, or results)

So storage seems to refer to the act, state, or place of storing something.

What I don't understand is why store also came to mean "shop." I can see how the verb developed the meanings "keep," "save," or "stock up," but I haven't found a satisfying explanation for how the noun came to mean a retail shop.

Is the "shop" sense historically related to the "keep/store" sense, or are they different words that later merged? If they are related, how did that semantic shift happen?

I have noticed similar-looking pairs such as band/bandage and pack/package (if those are valid comparisons), but I'm not sure whether the same process applies here.

What is the reason behind store having the meaning shop?

The first thing to note is that "store" is preferred in American English, while "shop" is used more in British English. As a native British English speaker, I can tell you that "store" is sometimes used, so they aren't exclusively from one dialect or the other. But your point is valid - they usually refer to the same thing.

It isn't unusual for nouns to come directly from a verb, or vice versa. For example, objects like a hammer, vacuum or comb share their name the verb action they are used for - you hammer with a hammer, comb with a comb etc. Places like a school, camp or shelter are also named as the verb action they are used for - you shelter in a shelter, camp at a camp etc. So, "shop" and "store" are not unusual in that respect.

"Shop" and "store" are both nouns and verbs, but from different perspectives. The owner of the store has stored items for sale, and the customer shops there. This is also not unusual - for example, some people might use the term "reception" (the area of a building/business where visitors arrive) interchangeably with "waiting room". These are also from two different perspectives, because the hosts receive visitors there, while the visitors wait there to be seen.

As a Brit, "shop" is bound to feel more idiomatic to me, because I shop in shops, but interestingly the etymology of the word reveals that the noun came first in that particular case (it meant "porch" or "shed" in Germanic and middle English), and the verb has been derived from it. But "store" has a wider use than just what the British call shops - for example, a business that is not a shop may have a store where they keep materials, stationery etc; an army store is where items are stored for collection and use. Neither of these kind of stores are "shops" because items are not for sale.

The suffix -age (as in storage) normally changes a verb to denote the result, process, collection, or place associated with it. As a result, they are often abstract, and usually non-countable nouns. This makes nouns like storage, postage, wastage etc. very different from their noun/verb counterparts, so the existence of "storage" doesn't really impact on the use of "store" as a countable noun and a verb.