In Aave/Compound, the interest rate is set in a two-step process. First, a certain utilization rate (% amount borrowed / amount deposited) is targeted. Then, a curve is hard-coded that aims to discourage utilization past the optimal level by sharply increasing the interest rate. The problem with this model is that the curve is fixed and cannot react to external market conditions.
Augmented Finance pools will still target an optimal utilization rate (e.g. 90% utilisation for stablecoins), but rather than doing so via a curve, we will allow interest rates to adapt dynamically to market conditions in real-time. The dynamic interest rates model is more responsive to changes in supply-demand conditions and thus achieves more stable utilization. It will lead to higher capital efficiency for both suppliers and borrowers.