A service pack (SP) is a collection of updates, fixes and/or enhancements to a software program delivered in the form of a single installable package. Many companies, such as Microsoft typically release a service pack when the number of individual patches to a given program reaches a certain (arbitrary) limit. Installing a service pack is easier and less error-prone than installing a high number of patches individually, even more so when updating multiple computers over a network.
Hence in short a SP is a roll-up of hot fixes with some strategic improvements from the engineering team
Now let’s go into more details about SP, Cumulative Update and Hot fixes
When a new version of a product is being developed, it may be made available to selected customers and community members for early testing and is sometimes called alpha builds of the product.
As development progresses and the product become more and more polished, it’s provided to a wider audience. This used to be called beta releases; for example beta 1, beta 2, etc. However a few years ago Microsoft changed the terminology for SQL Server pre-releases. They are now referred to as CTPs (Community Technology Previews). You can download the November CTP, for example.
As the product enters into it’s final stages before release, the feature set is complete and the product is undergoing final testing, it’s called an RC (Release Candidate).
After a product has undergone significant testing and it’s determined that no more changes will be made to the product before release, it’s sometimes said that the product has gone golden. It’s also called a GA (General Availability) release and once the bits been turned over to a company to mass produce the media (CDs, DVDs, etc), it’s called RTM’d (Released To Manufacturing).
Usually sometime around the RTM, the product version is “launched”. The timing of the launch may or may not have any correlation with the time the product is actually available for purchase. The launch has more to do with marketing and product feature education than availability.
Finally the product is released! It’s available for purchase.
Here comes the part you are looking for….
Over the period of time, Hot Fixes are created by the dev team to address specific product issues affecting certain customers. Sometimes the issue is so wide spread, a GDR (General Distribution Release) is issued so that all customers will receive the updates.
Since hot fixes and GDRs are designed to quickly address specific problems encountered by specific customers, they can be issued rather often. The rapidity of the hot fixes and GDR’s makes it impractical for many IT shops to keep up with the pace of the releases. So, a CU (Cumulative Update) is created that contains all of the applicable hot fixes. This makes it easier for customers who haven’t been directly affected by the issues that sparked the hot fixes to remain current.
Once a large enough collection of changes have been gathered, an SP (Service Pack) will be issued. Historically, SPs have also been the release vehicle used to deliver new features that were not ready at the time of GA. For example, Database Mirroring was made available in SP1. SP2 brought us the custom reports as in the Performance Dashboard. Microsoft has since administrators better understand the difference between a CU, IU, and SP.
CU = Cumulative Updates
IU= Infrastructure Updates
GDR=General Distribution Release
Bugs that have been fixed in SQL Server 2005 Service Pack 1 >> http://support.microsoft.com/kb/913090
Bugs that have been fixed in SQL Server 2005 Service Pack 2 >> http://support.microsoft.com/kb/921896
Bugs that have been fixed in SQL Server 2005 Service Pack 3 >> http://support.microsoft.com/kb/955706
Bugs that have been fixed in SQL Server 2005 Service Pack 4 >> http://support.microsoft.com/kb/2463332
Bugs that have been fixed in SQL Server 2008 Service Pack 1 >> http://support.microsoft.com/kb/968369
Bugs that have been fixed in SQL Server 2008 Service Pack 2 >> http://support.microsoft.com/kb/2285068
Bugs that have been fixed in SQL Server 2008 Service Pack 3>> http://support.microsoft.com/kb/2546951
Bugs that have been fixed in SQL Server 2008 R2 Service Pack1 >> http://support.microsoft.com/kb/2528583
Bugs that have been fixed in SQL Server 2008 R2 Service Pack 2>> http://support.microsoft.com/kb/2630458