Both embed methods are responsive. Nothing should introduce horizontal scrolling on the host page, at any width.
An iFrame embed renders inside a frame and reports its height back to your page. A script embed renders straight into your own DOM.
The editor generates the snippet for you. It carries the id, the container, and the loader that mounts the product on your page.
Every Timepath product has a stable id. That id is all an integration needs: the same id works for the iFrame embed and for the script embed.