Centrises used either a slower 68040 CPU than their Quadra siblings (25 MHz versus 33 MHz) or 68LC040 processors (no FPU) while Quadras (Quadra 605, which was introduced on the day the entire Centris line was killed, is the only exception) used full 68040 processors at higher speeds. IIvx used an '030 so doesn't really fit in. I suspect the term "Centris" as applied to the IIvx is just a matter of convenience for marketing because it was introduced months before the first real Centris was introduced.

Peace,

Drew