aptX, aptX HD, aptX Adaptive are the special coding of high-tech Bluetooth, which is dedicated to audio transmission; compared with the basic SBC, the sound quality has been improved.
I have actually tested that there is a big difference between SBC and aptX. If you have an aptX headset, you can try it. In the Bluetooth settings of the mobile phone, about advanced audio or aptX, the default is SBC, and you can hear the difference;
aptX LL :
aptX LL focuses on low latency, which can reach 40ms, which is almost the same as wired. Less than 70 ms delay the human body can not feel.
aptX HD can support 24bit 96KHz and 576kbps, which is much higher than ordinary one. In theory, the sound quality has been improved a lot;
aptX Adaptive is a new standard. The functions of aptX HD and aptX ll automatically adapt to different situations. It seems that there is no headset support for this. In my understanding, when playing games, it adapts to the low delay of aptX ll, while listening to music, it adapts to aptX HD.