不比 vs 没有 comparison usage
Your understanding is correct.

1. 他没有我高。-&gt; he &lt;  me
2. 他不比我高。-&gt; he &lt;= me


Comparing with the 1st one, the 2nd one is usually used for the situation to explain sb/sth is not bad relatively. Such as:

他不比我高。
-&gt; I'm as tall as him at least, he's not taller than me, connote that I'm not bad comparing with him.
本公司的技术水平已经不比国际上的一流水平差。
-&gt; Our technology level is not worse than international advanced level, connote that we're at the same level at least.