Difference between Major and Minor version in SharePoint 2010:

• Version numbers are the sequential numbers applied to lists and libraries when a file is created or changed.

• Major versions are appear as whole numbers( i.e., 1,2,3,4...etc), while Minor versions appear as decimal numbers( i.e., 0.1, 0.2, 0.3, ... etc)

• Lists should be always in Major version whereas Libraries can either be in Major/Minor version.

• Minor versions in libraries are assigned to documents that are in Draft status.  If a document is Published, it will increment to the next major version.  For example, if you publish version 2.51, it becomes version 3.0.