The two pickups are hard to comapare becasue they do different jobs.
First of all the most obvious difference is the fact the EMG's are active, giving them more gain. Secondly The
duncan distortion is a ceramic pickup where's the EMG 707 is Alnico meaning the interection between the pickup and the strings magnetically is different.
The resulting sounds are different and sound better in different situations.
Emg's for example are perfect for metal, and they really clean up when required, unfortinately they lack character while clean and can be described as sterile.
Duncan destortions however have a warmer distortion with a tuch more mud and have a smoother more subdued clean.