Plugins (for example a Shopify Theme App Extension or a WordPress plugin) add the experience to product and collection templates from the platform’s own admin. Embeds are a script tag plus a product reference that drop into any page. The SDK exposes the viewer, configurator and events to code.
All three render the same experiences from the same published products, so a brand can start with a plugin and move to the SDK without rebuilding content.
Why it matters
The integration path decides who has to be involved: for plugins and embeds, nobody technical.