SPFile.Versions.Count & SPListItem.Versions.Count

There is always a confusion between SPFile.Versions.Count & SPListItem.Versions.Count, as to which one to use and what is its purpose.

  

SPListItem.Versions.Count is always 1 more than SPFile.Versions.Count. The reason is SPFile consider the latest version as the current version and therefore does not include this in its version collection.

Thus, SPListItem.Versions.Count[1]  is equal to SPListItem.SPFile.Versions.Count[0].

if you go to  version history of a document , you will get a count equal to SPListItem.Versions.Count

Thus SPListItem.Versions.Count will give you, an exact version count of a document.