Thank you for the feadback, I used hp comparison tool but found not differences at all, except for some errors in their data (for example, in the file you have attached, 475 has RJ-11 but 476 has not?, 475 has hard drive but 476 has not? both have ADF for the scanner but 476 has additional ADF /in paper handling line/ but 475 has not?)
I had even talked with hp, and dealer, but got to known only that 476 is newer than 475 :-)