For me, in SE there is difference between weapons in frag and weapons in coop, as they appear to be less powerful in frag mode
(i am not sure about all of them, some are maybe even stronger - like Double Barrel, but some are surely weaker, like sniper... you can test playing Frag-Coop and find out) ... so far in FE i have tested and that difference doesn't exist that much)
I have also found difference in FE, where small bursts are stronger than actual fire... that applied to laser and tommygun... i was shooting some guys on XENOX with tommygun, and with small bursts he flew away really fast... for minigun i think it is the same because there is delay before starting of fire. It's possible to be the same for tommygun too... i dont know... it just gives a different feeling
... for laser ... - transporting AFK XENOX players had to be done fast so what better way than from above the map?
(well if you play coop that is) ... so i had to find a fast way to do this... and realized that firing in bursts laser was much faster than without... (i don't know where the hell is logic in this)... cannon was also not an option becoz in Sam's Space there appears to be too much friction!!)))
So anyway) what us coop players notice most about minigun is its ability to shoot in much longer range than any other bullet weapon in the game) while tommygun stops firing at a certain distance, the minigun continues to fire at at least 200 m above it.. or even more
P.S.: Sorry if that was a little off-topic too btw)