There are two types of ablatives that you can find around comparisons, the ablative of comparison that means "than", and the ablative of degree of difference, a mouthful to say, in which the ablative modifies the comparison. It's very common to treat this ablative like an adverb, multō, meaning "much" (or literally, "by much"). This video explains the nuts and bolts behind this.
91 rules of grammar cases nouns