反引号与$（）的输出不同

Question

以下代码：

url="http%3A%2F%2Fstackoverflow.com%2Fsearch%3Fq%3Durldecode%2Bbash"

line=`echo -e ${url//%/\\x}`; 
echo $line;

line=$(echo -e ${url//%/\\x}); 
echo $line;

产生：

httpx3Ax2Fx2Fstackoverflow.comx2Fsearchx3Fqx3Durldecodex2Bbash
http://stackoverflow.com/search?q=urldecode+bash

``和$（）是否会产生相同的结果？