To clarify the differences we are going to call the new syntax "Declarative Pipeline" and the existing full-imperative syntax "Scripted Pipeline".
Both are part of Pipeline and run on the same execution engine. The syntax is the only difference. Both can be used in a Jenkinsfile, both can be loaded from SCM.
It has been suggested that terms like "Generate Pipeline script" or "Load Pipeline script from SCM' were confusing because they imply that only "Scripted Pipeline" can be used. We need to remove "script" from these references:
"Generate Pipeline Script" -> "Generate Pipeline"
"Load Pipeline script from SCM" -> "Load Pipeline from SCM"