The jewelry example shows why ʿaks can press the proponent to identify a feature concealed by the apparent similarity. Ordinary clothes for use do not necessarily share the legally relevant category of gold and silver.
The ruling requires attention to the material, governing rules of zakat, and the role of use. Once a material distinction is established, the analogy cannot survive solely on the superficial similarity.
ʿAks and farq can overlap in practical debate, but ʿaks presses the proponent with the proponent's own precedent, while farq primarily identifies a relevant difference between original and new case.