Below content is taken from the Microsoft support site, https://support.microsoft.com/. Please visit to the official website to see the latest and updated information.
Cumulative update (CU)
- A roll-up update that contains all previous critical on-demand hotfixes to date. Additionally, a CU contains fixes for issues that meet the hotfix acceptance criteria. These criteria may include the availability of a workaround, the effect on the customer, the reproducibility of the problem, the complexity of the code that must be changed, and other topics.
Hotfix
- A single, cumulative package that includes one or more files that are used to address a problem in a product and are cumulative at the binary and file level. A hotfix addresses a specific customer situation and may not be distributed outside the customer’s organization.
RTM
- Usually means “release to manufacturing.” In the context of a product such as SQL Server, it indicates that no service packs or hotfixes were applied to the product.
RTW
- Usually means “release to web.” It indicates a package that was released to the web and made available to customers for downloading.
Service pack
- A tested, cumulative set of all hot fixes, security updates, critical updates, and updates. Service packs may also contain additional fixes for problems that are found internally since the release of the product and a limited number of customer-requested design changes or features.
