Major Updates - These are implemented on a larger scale to address specific issues and have a significant impact on rankings. They occur once or a few times annually, and websites are given advanced notice before the updates take place. Getting updates allows for a window of time to prepare so that rankings of well-established websites don't plummet as soon as the update goes into effect.
Broad Core Updates - Adjustments to a main algorithm can occur a few times a year and usually entail shifting the priority of some factors, such as quality of backlinks and loading speed.
Minor Updates - These are slight refinements on micro-algorithms that can occur daily to improve the relevance of search results and user experience.