To me it’s not.. it’s just slightly more efficient basically. You could argue the diodes may last longer too.
FC runs Samsung 301b diodes
FCE runs some bridgelux diodes
I think driver may be different brand also.
I run the FC E4800 and love it.. when I expand I will do the FCE series.
I think it’s just a way to make a bit more money on the name brand LM301B diodes everyone seems to think are so much better. Like you said they’re marginally better, and it’s mainly just efficiency I believe.
I say go FCE series personally.
I’ve got a few grows under them in diaries of ya wanna look