most USB mics are with 16mm back electret capsule, the 16mm capsule inside At2020USB is the same as the one in AT2020, the capsule inside AT2020/AT2020USB is better than other 16mm back electret capsules ..
Do yourself a BIG favor and stay away from usb mics and adapters.
They are basically made for PODCASTING (radio chat shows), not music recording.
The analog-to-digital converters in their mini-soundcard are mediocre for music.
The poor monitoring in them will give you fits trying to overdub new tracks.
The short cords will introduce a LOT of computer fan noise.