What Shopify sync apps can and cannot do
Every sync app on this platform reaches your stores through the same Shopify API. That means most of the boundary below is not a difference between vendors: it is a property of Shopify, and any app that promises past it is promising something it cannot deliver. Here is the honest line, so you can check any vendor against it, ours included.
Copied between stores without trouble
Product fields - title, description, status, tags, options - copy cleanly. So do variant fields: SKU, barcode, option values, weight. Available stock copies per location once you decide which location in the receiving store represents the stock you are sending.
Images copy when the product is first created in the other store. That is a deliberate limit in StoreTwin: replacing the image set of a product that already exists means removing images the other store may rely on, and Shopify treats that set as one value, all or nothing.
Copied only if you ask
Price is the obvious one. Two stores usually exist because they sell in different markets, and copying prices between currencies produces nonsense at best. StoreTwin keeps price off until you turn it on for that connection.
Metafields in your own namespace copy. Metafields owned by other apps in the receiving store - review scores, subscription settings, loyalty data - are compared and reported but never overwritten. They belong to that app, and a sync app rewriting them starts a fight that runs every hour and that nobody wins.
Not copied, and not by our choice
Orders and customers. Shopify does not let an app recreate an order in another store as it was, and a customer record carries consent and marketing state that does not transfer between stores. StoreTwin does not request access to either: the permission screen you see at install has no line about orders or customers at all.
Discounts, shipping profiles, tax settings, themes and apps: these are store configuration rather than catalogue, and they live behind different APIs with different rules. A catalogue sync app that claims to keep your whole store identical is describing something else.
The part vendors rarely mention
Copying is the easy half. The hard half is knowing, a month later, that the copy is still correct - after a missed webhook, a bulk edit in the wrong store, a variant renamed by a supplier feed, or an app that paused for a day and came back.
This is where apps differ, and it is worth asking about directly: how does the app tell me my stores disagree today, and does it name the product and the field? StoreTwin answers with an audit: hourly for what changed, nightly for the whole catalogue, with a report that names each difference and both values.
Questions worth asking any vendor
Does it ever delete anything in my store? Under what circumstance does it create a second copy of a product it should have recognised? What happens when both stores changed the same field? How do I see, without writing to support, whether the stores match right now? What does it do when it is not sure - guess, or stop and ask me?
For StoreTwin the answers are: never deletes, stops instead of guessing, the source store wins because the sync is one way, and the difference report is on the connection page and in a weekly email.