不= no,not,nope（Negative mood）, or prefix like "un-" in English.
不好 (not good), 不高兴(unhappy), 不想 (do not want to), 不是 (is not), 不 (no)
没有= haven't, nothing, not have; there is not; without
- 我没有傻到去相信他。 I was not fool enough to believe him
- 没有唇枪舌剑，这场纠纷就解决了。The dispute was settled without acrimony.
- 你所说的没有一句是实话。There is not a particle of truth in what you said.