御～
ご～ · go～ · JLPT N4 · noun
honorable ~
go- = the polite GO-ahead prefix: 御 marks a word as honorable
御 originally meant to drive or govern, then became a marker of respect for what belongs to someone above you. Read go- before Chinese-origin words (ご飯 gohan, ご家族 gokazoku) and o- before native Japanese ones (お水 omizu).
おん～ · on～ · JLPT N2 · noun
honorific
On + or sounds like honor: 御~ adds an honorific tone, as in 御飯 (gohan).
御 originally meant to control or manage, then came to mark things belonging to a person of high status. That origin is why it attaches to polite words like 御飯 (gohan).