Different types of Oracle Applications Updates.

Oracle Applications organizes updates based on granularity:

One-off:
This is the most granular update required to change a particular behavior or fix a particular defect. These updates tend to be smaller, but due to product dependencies may be large.

Mini-pack:
This is an aggregation of all updates for a particular product, such as General Ledger (GL). The updates are aggregated into a single, easily applied patch that will take you to the latest code level for a particular product area. Mini-packs are named successively by letter. For example, 11i.GL.A, 11i.GL.B, etc. Mini-packs replace the previous concepts of Applications patchsets, mega-patches, or rollups.

Family Pack:
This is an aggregation of all updates for a particular family, such as the Procurement Family (PRC_PF), which is made up of Purchasing, Internet Procurement, Supplier Scheduling, and Internet Supplier Portal. The updates are aggregated into a single, easily applied patch that will take you to the latest code level for the entire product family.
Family packs are named successively by letter. For example, 11i.PRC_PF.F, 11i.PRC_PF.G, etc.

Maintenance Pack:
This is an aggregation of all updates for the entire E-Business Suite, including all ERP and CRM products. The updates are aggregated into a single, easily applied patch that will take you to the latest code level for the entire E-Business Suite. Maintenance Packs are numbered as point releases, 11.5.3, 11.5.4, 11.5.5, etc. Additionally, for customers not yet on 11i, the Rapid Install is repackaged at each Maintenance Pack level.

Oracle Applications updates can also be classified by type:

Interoperability patch:
This is an update to Oracle Applications code that will enable a change to the underlying technology stack. For example: Applications Release 11i interoperability patch for Oracle 9i, Applications Release 11i interoperability patch for Developer 6i patch 9, etc.

Diagnostic patch:
This type of patch is intended to gather additional information about a particular issue being encountered at a customer site. It is often used when the issue cannot be reproduced on-site at Oracle.

Translated update:
This is a translated version of a patch. It contains only the components requiring translation. Language independent portions of a base patch are not included in a translated patch, therefore you must always apply the base US patch as well as the translated patch.

Product Introduction:
This type of update introduces a new product to a release using the patching infrastructure. Examples include Oracle Process Manufacturing for Release 11.0, and Oracle Enterprise Asset Management for Release 11i.

Note: All patches can be downloaded via Oracle MetaLink for any supported platform or language. Customers can query a specific patch, or they can query for patches based on Release, Products, Platforms, or Languages. The search can also be limited to high priority patches, mini-packs, or patches not in the latest product mini-pack. The patch READMEs can also be viewed online.