Difference between Give something the go-by and Let something go by

give something the go-by—

1. evade or ignore smth.:

• There is one other subject to which I would like to refer, lest I should be accused of deliberately giving it the go-by.

2. surpass or outstrip a car, boat, etc.:

• As we gave the staggering rice-boats the go-by, I reflected that I was looking upon the River of the Lost Footsteps.

let something go by—pass up a chance for smth.; fail to make use of smth.:

• Don’t let the opportunity go by to tell them why it’s important to be honest.