You might wonder why you have 不比 (bù bǐ) for negative comparisons when you already have 没有 (méiyǒu) for comparisons. The answer is that they're not exactly the same thing! 没有 should be your "go to word" for expressing "not as... as...," but there are cases where 不比 (in all of its subtle glory) is a better choice.
To say that something is not more adjective as another, you can use 不比 (bù bǐ). No snickering, please. 这些形容词经常是undesirable一类。
A + 不比 + B + Verb + 得 + Adj.
This is similar to, but not exactly the same as comparing with 没有. Note that "Verb + 得" can also placed before 不比.
不比 and 没有 are not exactly the same. 没有 means "not as... as," whereas 不比 is a direct negation of 比, meaning "not more... than." Compare the following two English sentences:
You'd probably be more upset to hear the former from a friend than the latter. The two above sentences in Chinese are: