Oh boy, have I found some real oddities on the 1900 census in particular.
In general, I have found ethnic names to be different in different years, probably both due to whomever spoke to the census enumerator, and how the enumerator heard accents and nicknames.
I have been trying to find my wife's Russian great grandfather, whose real name I am not even sure of after all the changes in the documents I do have!
Bad transcriptions don't help either, of course. My Tierneys were lost for a long time as Freeneys, Fierneys, Deeneys. I blogged about one particularly bad 1910 transcription for my wife's family:http://currach.johnjtierney.com/2011/08/bad-transcription-ba...
Good luck with your searches!