In the Family Search, there are several different types of records. The IGI is normally taken frommicrofilmed copies of records. These are more accurate than the compiled records submitted by individuals (either LDS chuch members or the general population).
Normally the IGI records show where they were obtained and you can verify the accuracy. The compied records may also have sources but these are normally individuals who have taken IGI data and/or other data sources and submitted the results to the LDS in the same manner that you may submit your research to your own web site or a FTM user may submit their research to Genealogy.com.