https://jenkins.io/doc/book/pipeline/syntax/#compare

and

https://jenkins.io/doc/book/pipeline/syntax/#scripted-pipeline

Scripted is a general purpose DSL and executed from the top of a `Jenkinsfile` downwards like most traditional scripts in Groovy.

E.g. of if/else and try/catch/throw – https://jenkins.io/doc/book/pipeline/syntax/#flow-control

Notes:

• Declarative pipelines have a `pipeline` block. e.g.

pipeline {
    /*... code here ...*/
}

• executing a scripted pipeline in a Declarative Pipeline

a script step takes a block of Scripted Pipeline and executes that in the Declarative Pipeline