Not to be a smartass, but you post the website where they have all the differences, then ask us what the difference is?
Here, I'll copy it for you:
MobilePre
2 x 2 16-bit/48kHz analog I/O
2 microphone inputs (XLR balanced) with 48v phantom power
stereo microphone input (1/8”)
2 high-impedance instrument/line inputs (balanced/unbalanced 1/4” TRS)
2 mono line outputs (1/4” @ -10dBV)
stereo line output (1/8”)
stereo headphone output with level control knob
gain control knob for each input channel (+40
dB max)
zero-latency hardware direct monitoring (mono/stereo) with software level control
USB-powered for total mobility
includes Maximum Audio Tools software bundle
Duo
2 x 2 analog I/O
2 preamp channels each featuring:
• mic input (XLR)
• amazing available gain of 66dB
• 20dB pad
2 line inputs (1/4” TRS)
global 48V phantom power
2-channel S/PDIF coaxial digital output (16- and 24-bit PCM)
up to 24-bit/96kHz performance
balanced/unbalanced operation
includes Maximum Audio Tools software bundle
frequency response: 22Hz-22kHz
dynamic range: 104dB (A-weighted)
signal-to-noise ratio: 100dB (typical, A-weighted)
THD: 0.002%
USB recording: • 16-bit/44.1kHz > 4-in/4-out
• 24-bit/44.1kHz > 4-in/2-out or 2-in/4-out
• 24-bit/48kHz > 4-in/2-out or 2-in/4-out
• 24-bit/96kHz > 2-in or 2-out
