cron - What is the difference between Poll SCM & build periodically in Jenkins?

Question

In both it takes cron expression as input, so what's the actual difference between these two.

question from:https://stackoverflow.com/questions/41114251/what-is-the-difference-between-poll-scm-build-periodically-in-jenkins

Answer 1

Poll SCM periodically polls the SCM to check whether changes were made (i.e. new commits) and builds the project if new commits where pushed since the last build, whereas build periodically builds the project periodically even if nothing has changed.