Is High Sierra the same as Sierra?

cmcinnc:

Note these macOS system versions of downloadable installers are available

online from support site; several layers of information are presented here:

• How to get old versions of macOS - Apple Support

https://support.apple.com/en-us/HT211683

Your question is among other answers provided on this page; with links.

'High Sierra' (10.13.6) is newer than older 'Sierra' (10.12.x) ~ in a progression.

Instructions on how to get and use these downloadable installers. These

will then go to Apple Servers, to get and install a chosen installer. Expect

this to take time; as details are important, to achieve workable results.

No, they are different operating systems.