an electron can have a spin +1/2 or -1/2. A positron is identical to an electron except that it has a positive charge. Hence it is the electron's antiparticle. A neutrino has a spin of +1/2 while an antineutrino has a spin pf -1/2. I think that we should stop using the term antineutrino. Because the neutrino is its own antiparticle.