This can be explained with the following example: The form submission tracking on your website is set up to track events and goal on form submission. If a form is submitted, it will be counted as a goal conversion and also as an event.
However, if you decide to resubmit the form because you thought you filled it wrong the first time, for example, the re-submitted form will still be counted as a single goal conversion but the total number of events will be considered as two. This is why goal conversions are sometimes less than actual events.
