Both are evolutions of the EP6DT (150hp, on 207 GT) and EP6DTS (175hp, on 207 RC and GTI). I'm afraid I don't know what was changed, but perhaps more than just software.
The difference between the EP6DT and EP6DTS was a different turbo and software.
In those new engines you mention they increased power to 155hp and around 200hp I believe.
See
Prince engine - Wikipedia, the free encyclopedia
"At first, there were two versions on offer - the THP150 and THP175, also known as the EP6DT and EP6DTS respectively within Peugeot. The first was later updated as EP6CDT and also a THP163, EP6CDTM.[6] There is also EP6CDT MD - with little bit lowered CR"
