Seals go by several names, and the difference is not the shape — it is whether it is registered and where it is used.
Registered seal (인감)
A seal filed with a local government office. Pressed together with a seal certificate, it lets the state vouch that the person is who they claim to be. Required for property sales, inheritance and mortgages. Nothing about the seal itself is special — registration is what makes it one.
Everyday seal (막도장)
An unregistered seal, used at bank counters, for parcels and on internal documents. It is not legally meaningless: a contract sealed with one is still a contract. But if someone later denies pressing it, proving otherwise is hard.
Company seal (직인)
Pressed in a company's name. Round seals go on contracts, certificates and official letters; square seals go on invoices, quotations and delivery notes. A corporate registered seal is filed with the registry office.
So where does an image seal sit
What you make here counts as an everyday seal. It cannot serve as a registered seal, but it is entirely adequate for internal approvals and routine business paperwork.