Helix 5 questions

[MThook]

what's the difference between the following fish finders and what is Chirp

What I'm looking for is a unit to put on the front of the boat and would probably only need down image, I have SI on the console
They are about the same price
Any help would be welcome

Humminbird-Helix-5-G2-Chirp-Sonar-GPS-Combo-Humminbird-Helix-5-G2-Chirp-Sonar-GPS-Combo/190394676
Humminbird helix 5G chirp Sonar/GPS

[rnvinc]

HELIX 5 G2 CHIRP Sonar GPS Combo is the current production HELIX 5" Sonar unit (CHIRP 2d/Temp/GPS mapping) ...

There is no HELIX 5G CHIRP Sonar GPS (this is mis-labled by whichever outlet you see this on) ...

HELIX 5 Sonar GPS Combo is the previous production HELIX 5 Sonar unit (83kHz/200kHz fixed frequency 2d/Temp/GPS mapping) ...
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CHIRP sends a frequency range sound pulse into the water with each individual Ping ... (Example 75kHz-95kHz instead of fixed frequency individual Ping 83kHz) ...

This sonar Ping technology (CHIRP) allows more data collection, with better target separation, with less associated noise ... captured with each individual Ping ...

Rickie