Question Google Dialer Lookup Providers

I decided to give Google's updated Dialer a test drive, but there is one question I simply have not been able to find a simple answer for:

What is the difference between OpenCnam, Whitepages, Yellowpages and ZabaSearch for reverse lookup providers?
Spiricore's Super Safe Root-To-ROM Guide
for Sprint's Samsung Galaxy S4 (SPH-L720/jfltespr)
Baseband: NAE Recovery: Philz 6.48.4
ROM: Carbon ROM Nightlies
GApps: Paranoid Android 0-Day
Mods: Xposed Lux Viper4AndroidFX 2.3.3.0 Mother of All Ad Blocking


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