Suppose two drinks have the same color, but only one is intoxicating. Similar color or packaging does not make their legal rulings identical.
Irrelevant resemblance: the drinks are red or kept in similar bottles.
Potentially operative resemblance: they share the intoxicating property relevant to the established prohibition.
The central question is therefore which feature actually functions as the ‘illah? The source later identifies the Qur’an, Sunnah, ijma‘, and ijtihad as ways of knowing a legal cause. Choosing the wrong feature undermines the analogy even if the argument sounds neat.