Slitherine

Something I've been wondering about: Does a Defensive Spear unit have any defensive advantage over an Offensive Spear unit? Or is an Offensive Spear unit always strictly better?

This is assuming morale, armor, etc is the same for both of course.

Defensive Spear only get their 100 Impact POA when defending, or charging other Defensive Spearmen. In other words,

Defensive Spearmen charging Offensive Spearmen are at a 100POA disadvantage. If the Offensive Spearmen charge them, they are even at 100-100POA.

Defensive Spearmen charging Massed Archers are at a 0-0 even POA. If the Massed Archers charge the Defensive Spearmen, the Spearmen are at a +100POA advantage.

Against cavalry, they are identical, because Offensive Spearmen get no Impact POA for charging Lancers/Knightly Lancers/Heavy Chariots/Elephants, same as Defensive Spearmen.

In melee, they are equal. Note that Offensive Spearmen who charge the enemy have a chance of pushing the enemy back, and the enemy cannot Fall Back from them after losing melee. Enemies can Fall Back after losing to Defensive Spearmen, regardless of who initiated the melee. This can be a good or a bad thing, just depends on the situation.

Defensive Spearmen are cheaper.