Psalm 23

The LORD is my shepherd;

there is nothing I lack.
.
.
Even though I walk through the valley of the shadow of death,

I will fear no evil, for you are with me;

your rod and your staff comfort me.

Doesn't "rod" and "staff" seem redundant?

A quick trip to the internet suggests some differences.

This Basque sheep herder is holding a rod in his right hand and a staff in his left.

The rod is more than a 33" long walking stick.  It was used for defense and for discipline.  As in the phrase "Spare the rod and spoil the child."

The staff is more than a 72" long walking stick.  It was used for defense and also to gather, to scoop up lambs from ledges and to "hook" ewes that would otherwise flee in their mindless, animal panic.  Sheep are not very smart.

Just as sheep are some of the dumbest animals on the planet, sheep herders are some of the toughest.  Modern shepherds are likely to have a Winchester 30-30 or an SKS.  They have more range than the 33" rod.

The author of Psalm 23 is telling us that we do not need to fear evil because God defends us AND because we willingly submit to God's discipline (a key marker of being a member of any organization) AND because we know that God will be there to collect us should we do something stupid that would lead us astray.

The shepherd leads his sheep.  He goes where they go.  He lives where they live.  It is not a "commuter" kind of job.

Key point:  AND, not "or if".