I would not try to compare with 1.4.4, despite only some month between the releases, the actual difference is about a full year.
1.4.4 only is on the 1.4 branch which was created a year ago, and the 1.4 branch only received a subset of all the changes made since.
You will need an svn client to get different sources from trunk (step by step / or intersecting, by going back half way since the branch, and then keep halfing).
To anyone, it is possible to run the SVN version of Lazarus from within Lazarus?
- Start trunk as a 2nd install using --primary-config-path=new_conf_dir
- build trunk (with debug info) / dwarf if you have a newer debugger.
then open the project ide/lazarus.lpi (from the trunk sources)
you can do that with the 1.6 IDE or with the trunk ide.
In menu Run > Run Params make sure you point the "host application" to the trunk lazarus executable.
then press F9.