There is virtually no difference between the Rondo of Blood for PC-Engine and Rondo of Blood for Wii.
Features:
-Introduction in German with Japanese Subtitles
-All Cutscenes in Japanese (including all endings)
The differences are between these versions and the DraculaXChronicles unlockable for PSP, which features the following:
-Introduction in German, English Subtitles
-All Cutscenes are in English, dialogue being different than the remake's dialogue. No subtitles
However, I've not played DXC in quite a while so I cannot fact-check myself and I'm going on memory alone. I always play the Wii version.