Scenario 1: I've been playing around lately with a CI tool Jenkins, to integrate my Selenium WebDriver tests using Maven. I understand continuous integration (with respect to testing) is a concept where tests are triggered automatically, as soon as some build (let's call it Build#666) is checked in by the developers. This helps us identify bugs at the early stages.
Scenario 2: Now suppose I run the same tests without using Jenkins. Say I don't even use Maven, I just right-click on my TestNG suite and run it against Build#666 (meaning I'm manually initiating my automated tests to run as soon as the code for Build#666 is checked in).
Apart from the fact that Jenkins allows the tests to be run automatically (without manual intervention like in Scenario 2) and has features to schedule tests at a desired time, what is the biggest difference?
→ Can I consider also Scenario 2 to be continuous integration, as I am deploying the same tests against the same build, but I don't use a CI tool, but do it manually?