请教bu not 和rather than的区别

xiaoyue45084508

OG 264. Scientists believe that unlike the males of most species of moth, the male whistling moths of Nambung, Australia, call female moths to them by the use of acoustical signals, but not olfactory ones, and they attract their mates during the day, rather than at night.
(A)    by the use of acoustical signals, but not olfactory ones, and they attract
(B)    by the use of acoustical signals instead of using olfactory ones, and attracting
(C)    by using acoustical signals, not using olfactory ones, and by attracting
(D)    using acoustical signals, rather than olfactory ones, and attract
(E)    using acoustical signals, but not olfactory ones, and attracting
Choice D, the best answer, is concise, maintains parallel structure, and clearly conveys the comparisons being made between the two types of moth. In A and E, the comparison between most male moths and the male whistling moth is not clear. The use of but not does not clearly convey that most other moths use olfactory signals; rather than would be preferable, as well as parallel to rather than at night. In A, the phrase by the use of is unnecessarily wordy, and the insertion of they is not required. In E, the final verb should be attract (parallel to call), not attracting (parallel to using). Choice B violates parallelism with by the use of... instead of using, as well as with call... and attracting. Choice C distorts the meaning of the original with its suggestion that male whistling moths call female moths to them both by using acoustical signals and by attracting their mates during the day. The insertion of using in not using olfactory ones is unnecessary.

A和E选项中OG解释bu not 的意思没太明白，哪位能解释一下bu not 和rather than的区别？
谢谢！

nina23

表示  不是。。。而是  得有
...,not..
not.. but
...rather than...
...instead of...

but not 没查到有这个词组，应该是  但不是。。。 得意思，不是作者想表达得意思，或者说用BUT NOT说起话来很笨拙。

请多多指教：）

AMBER513

看一下！