What do the different formations do?

[Cotton]

Do they make a differnece? Does one formation counter another?

[Freagarach]

Nothing. ^^

(Not yet: https://trac.wildfiregames.com/ticket/3523)

[Player of 0AD]

They place your units in a certain way.

For example the box formation puts your melee troops at the edge and your ranged units in the center, even ranged cavalry.

The closed formation puts your melee troops at the front and your ranged troops at the back, but maybe it puts ranged cavalry in the very front.

The battle line puts your cavalry at the flanks.

Etc