What are the differences between a neutrino and an antineutrino?

What are the differences between a neutrino and an antineutrino? What are the conserved quantities in neutrino scattering? Complete the missing particle in vμ + e→ μ + ?. If neutrinos are massless, what is the direction of their spin? And for anti neutrinos? The Universe is full of neutrinos at a temperature of about 2 K. What is the neutrino average speed if their mass is 50 meV?