server 10.1, server 1.2 and server 2

[3mors]

In internet I found this three versions of mac os x server:
macos x server 10.1
macos x server 1.2
macos x server 2

Can someone explain me what they are?
Are the same version?
Which version is the newer?
And, if they are different, is there a free update, as I have server 10.1 version?

Thanx

 

[paulboy]

10.1 is the newsest version. The others are older.

Does anyone have the build version for 10.1 Server final? Is it 5k7?

Thanks