Why is the keyboard navigation and selection different for a group of checkboxes vs radio?

We are working on a multi-step survey flow that involves both single select radio options and multi-select checkbox options. We want to make sure it is easy to use for Keyboard users and have been looking at the W3 documentation.

Following the W3 guidelines, for a radio form you arrow through the options but for a checkbox form you tab through the options.

Why is the standard approach is to navigate and select these differently on a Keyboard?

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References below

https://www.w3.org/TR/2017/WD-wai-aria-practices-1.1-20170628/examples/radio/radio-1/radio-1.html

https://www.w3.org/TR/wai-aria-practices/examples/checkbox/checkbox-1/checkbox-1.html