how often does ZIP not equal ZCTA?

USD Mapper has a Zip code to ZCTA crosswalk
ZIP Code to ZCTA Crosswalk
www.udsmapper.org/zcta-crosswalk.cfm

Some papers:

What are ZIP Code Tabulation Areas? March 10, 2016 by Bernie Langer
www.policymap.com/.../
More than half of all ZCTAs share more than 90% of their area with their associated ZIP Code. Over 70% of ZCTAs share at least 80% of their area with their ZIP Codes. 11% share less than half their area with their ZIP Code. Sometimes, the ZCTA is a small piece of the ZIP Code, sometimes the ZIP Code is a small piece of the ZCTA, and sometimes they’re just in different places.


On the use of ZIP codes and ZIP code tabulation areas (ZCTAs) for the spatial analysis of epidemiological data. Tony H Grubesic and Timothy C Matisziw. International Journal of Health Geographics20065:58. DOI: 10.1186/1476-072X-5-58
ij-healthgeographics.biomedcentral.com/.../1476-072X-5-58
This paper describes a few problems using ZCTAs and ZIP codes, and some special mismatch of ZCTA and ZIP codes, but uses 2000 census data and privately constructed geographies.


What is the difference between ZIP code "boundaries" and ZCTA areas?
Phil Hurvitz <phurvitz-at-u-dot-washington-dot-edu> 2008
ESRI Maps 2007. Census Tiger Lines 2000
King County, Washington.
gis.washington.edu/.../index.html
talks a little about ZCTAs and ZIP codes.

USD Mapper has a Zip code to ZCTA crosswalk
ZIP Code to ZCTA Crosswalk
www.udsmapper.org/zcta-crosswalk.cfm

Some papers:

What are ZIP Code Tabulation Areas? March 10, 2016 by Bernie Langer
www.policymap.com/.../
More than half of all ZCTAs share more than 90% of their area with their associated ZIP Code. Over 70% of ZCTAs share at least 80% of their area with their ZIP Codes. 11% share less than half their area with their ZIP Code. Sometimes, the ZCTA is a small piece of the ZIP Code, sometimes the ZIP Code is a small piece of the ZCTA, and sometimes they’re just in different places.


On the use of ZIP codes and ZIP code tabulation areas (ZCTAs) for the spatial analysis of epidemiological data. Tony H Grubesic and Timothy C Matisziw. International Journal of Health Geographics20065:58. DOI: 10.1186/1476-072X-5-58
ij-healthgeographics.biomedcentral.com/.../1476-072X-5-58
This paper describes a few problems using ZCTAs and ZIP codes, and some special mismatch of ZCTA and ZIP codes, but uses 2000 census data and privately constructed geographies.


What is the difference between ZIP code "boundaries" and ZCTA areas?
Phil Hurvitz <phurvitz-at-u-dot-washington-dot-edu> 2008
ESRI Maps 2007. Census Tiger Lines 2000
King County, Washington.
gis.washington.edu/.../index.html
talks a little about ZCTAs and ZIP codes.

Thanks everyone for the suggestions and references!