As has been mentioned, 'Sephirot' and 'Sephiroth' are two totally different characters/ideas. Sephirot was one of the Warring Triad/Gods of Balance in FFVI (in the original Ted Woosely SNES translation he was simply called 'Fiend', hence his subtitle), and has absolutely nothing to do with FFVII's infamous main antagonist, despite having a similar name taken from the Kabbalah (and even SE are aware of this and have joined in the fun at teasing the reference: the achievement for completing Sephirot's Extreme mode is 'Veni Veni Venias', referencing a line taken from One-Winged Angel, Sephiroth's famous final boss theme in FFVII. ).

But there is literally no direct connection between the two other than a shared etymology of the name.