Basis is spot minus futures, and forward market is spot price lower than futures price. The strength of the basis has nothing to do with the forward market, as long as the spot is better than the futures (that is, the spot increase is greater than the futures, or the spot decline is less than the futures decline, or the spot increase is the futures decline), the basis is strong.

Basis is generally said to be strong or weak, big or small, strong means expansion and weak means contraction. It has nothing to do with absolute value.

Similar to the basis difference is the price difference, but the price difference is high MINUS low. The price difference is an absolute figure.