Source: https://headphonesaddict.com/best-noise-isolating-earbuds/
There is quite a difference between noise isolation and noise cancellation that most people are probably not aware of.
Passive noise isolation isolates all outside sound, generally 25 dB – 30 dB, so if you want to lower all outside noise and just focus on your music, this is the best option.
Active noise canceling works slightly differently, it uses a microphone to record all low frequency noise, like the humming of a plane or helicopter engine (active noise canceling was first developed for helicopter pilots) and then sends the opposite sound to your ears through headphones to “cancel” it. This is a greatly simplified explanation. In the end, it usually cancels around 15 dB of noise.
Noise canceling headphones won’t cancel people talking next to you, or loud music, they are mostly used for canceling annoying background noise and not the “annoying people”.
Noise canceling is great if you want to remove the background noise, but still want to hear what people are saying. So this is useful if you’re on a plane and want to know when the dinner is going to be served, but find the jet engines too loud.
Additionally with lower quality, noise canceling headphones, the sound can be distorted which is one of the bad effects of this technology.
Generally, headphones with sound isolation have better sound quality, but this isn’t an exact rule.