Balance, equilibrium, equipoise, poise, tension are comparable when denoting the stability or efficiency resulting from the equalization or exact adjustment of opposing forces.
Balance suggests a steadiness that results when all parts are properly adjusted to each other, when no one part or constituting force outweighs or is out of proportion to another.
Equilibrium may be interchangeable with balance, but is more often restricted to a mechanically produced or producible property deriving from a thing’s construction, support, or relation to external forces and then often suggests a tendency to return to an original position after disturbance.
Equipoise suggests perfection of balance or stability of equilibrium.
Poise denotes an equality of opposing or different things or forces and often implies a state or an appearance of perfect balance or serenity especially of mind.
Tension in this relation implies strain, either a pull from both ends or an outward pressure in every direction, of such equality that there results a tautness without undue strain at any point; applied to a mental condition it implies an inner balanced vital opposition of moral or intellectual forces, powers, or qualities.