Comparing ACS data from different geographic levels (ZCTA vs. census tracts)

Hi all, I am working with the 2009-2013 ACS 5-year estimates detailed tables, and have a general question about comparing ACS data at different geographic levels. I have downloaded ACS data at both the census tract and the ZCTA levels. Does anyone know whether the same raw data is used for all of ACS's geographic levels (i.e. whether I should expect the ZCTA and census tract ACS data to be "equivalent"), or if the data from these two geographic levels draw from different samples? I am primarily asking because I am planning to crosswalk both of these datasets to the 5-digit ZIP code level, and would like to know what to expect when comparing the resulting numbers to each other.