This post defines the several files type which can be created for the Windows Installer technology like .msi, .msm, .cub, .mst, .idt and .pcp files.
.MSI -> .MSI file is Windows Installer installation package. It is a database file which is used to manage the various states of the application like adding, changing, or removing it from a computer.
.MSM -> .MSM is a Windows Installer Merge modules, which are pre-compiled libraries of components like files, registry, and other system changes that installs a discrete portion of the application.
Read this article to understand, how an Merge Module (.msm) works!
.MSP -> .MSP is a Windows Installer Patch file used to distribute small updates of .MSIs.To know more on Patches refer this article
.MST -> .MST is a Windows Installer transform file that makes changes to a pre-existing .MSI. A transform encapsulates all the changes which can be made to a base msi and hence it enables to maintain a SINGLE installation FILE and changes separately in the TRANSFORM file. An Example, having a single MSi for Office product, Creating two different Transform files for different licenses. Thereby ensuring that, the same package can be used in 2 different divisions. This will also ensure that, the base msi package is never changed.
.IDT -> .IDT is an Exported Windows Installer database table which can be removed from one database and imported to another database. Using this, you can copy a table alone into a new MSI package.
.CUB -> .CUB is a Validation Module that contains Internal Consistency Evaluators in a database which in turn evaluates databases.
For more information on Package Validation .Cub files, check here
.PCP -> .PCP file is a Windows Installer patch creation file that contains the configuration information that patchwiz.dll requires to create a patch.
For Using Patch Creation Tool in Wise Package Studio, Read this!!