Question about Extensions pdf

[Jimmie Houchin]

I've downloaded and started printing out some of the material to read.
There are 2 different Extensions pdf's.

They are:

Erlang Extensions 4.4                     EDE Team    1997-05-21
and 
Erlang Extensions Since 4.4 version 4.9   OTP Team    1997-05-21

I don't see much difference between the two other than the later also
contains chapters on 'includes' and 'miscellaneous'. They both have the
same date. But the title of the later, says since 4.4. This seems to
denote that it is in addition to the other, but they are dated the same.

Am I missing something. Do I only need the later and not the former?

Thanks for any clarification.

Jimmie Houchin