Plus + adverb + que conveys the idea of 'more ... than'.
moins + adverb + que the idea of 'less ... than'.
Aussi + adverb + que conveys the idea of 'as ... as.'
Note that mieux (better) is the irregular comparative form of the adverb bien (well). The other comparative forms of bien
are regular (moins bien que, aussi bien que).
In French as in English, the superlative is a way to express a maximum or minimum quality or capacity: 'the fastest', 'the least fast'.
formation:
To form the superlative of an adverb, the masculine singular form of the definite article is always used: le, followed by plus (more) or moins (less) before the adverb. Note that the superlative of an adverb has only one form.
Le mieux (the best) and le moins bien (the least well) are the superlative forms of the adverb bien (well).