Most phones and media players have both USB and auxiliary outputs, sometimes referred to as aux or headphone jacks. Both deliver music from a phone to a car or home stereo, but they differ in how they work. We compared the two so you can choose the best one for you.

The main difference between a USB (Universal Serial Bus) connection and an auxiliary input is that USB cables transmit digital information, while auxiliary cables transmit analog signals. USB cables transmit data like you would to a computer, while auxiliary cables transmit audio like you would to an amplifier or headphones.

The type of cable you use depends on your speaker system and setup. USB cables are generally more convenient and provide better sound, but are only available on digital systems. Auxiliary cables are useful in situations where there is no USB or digital interface, such as an old car, turntable, or home theater receiver.

In some cases, USB controls playback from the device you’re connected to, such as a car stereo. Because auxiliary jacks only carry analog audio signals, you often don’t have the same degree of two-way functionality.