Question On Download of Patch 1.4b

[Bent Periscope]

I bought the DVD in 2005 in the USA.

I want to finally patch to 1.4b but the download site has to DVD patches.

What is the difference between:
- silent_hunter_3_dvd_1.4b_s.exe (http://files.filefront.com/silent+hunter+3+dvd+14b+sexe/;13453993;/fileinfo.html)
and
- silent_hunter_3_dvd_1.4b_a.exe (http://files.filefront.com/silent+hunter+3+dvd+14b+aexe/;13453963;/fileinfo.html)?

Thanks,

BP