What this does: it measures how far apart two values are, as a percentage of their average — neither value is treated as the "base", so A vs B gives the same result as B vs A.
Example: two shops quote ₹1,800 and ₹2,200 for the same item. Value A = 1800, Value B = 2200 → 20% difference. Useful for comparing prices, quotes, or readings where neither number is the "original".