To create a tool from Snap-Ins, a user must get the Snap-Ins in the first place. Vendors will likely ship Snap-Ins in groups called packages. For example, a product like Windows NT itself would include one or more packages. Additionally, other vendors could ship products composed entirely of packages of Snap-Ins.
Grouping into packages provides convenience for download and installation. When autocode download is added to MMC (post-PDC), it will download packages rather that Snap-Ins. This permits several Snap-Ins to share core DLLs so that these (possibly sizable) DLLs do not have to be placed in every Snap-In.