Sexfoil is a coordinate term of huitfoil.

In heraldiccharge|lang=en terms the difference between sexfoil and huitfoil

is that sexfoil is (heraldiccharge) a stylized flower or leaf with six lobes while huitfoil is (heraldiccharge) a stylized flower or leaf with eight lobes; an octofoil.

As nouns the difference between sexfoil and huitfoil

is that sexfoil is (heraldiccharge) a stylized flower or leaf with six lobes while huitfoil is (architecture) a symmetrical shape which forms the overall outline of eight partially-overlapping circles of the same diameter.