A sperm, if it encounters the right mix of chemicals in the right conditions, will grow into a human being.

So a sperm on its on won't grow into a human being, in other words? As in, you are not eliminating a potential life because the sperm on its own does not have the potential to be a human being?

An embryo, if it encounters the right mix of chemicals in the right conditions, will grow into a human being.

Left in normative circumstances, the embryo grows into a human being, It has the POTENTIAL to be a human. A sperm, left in normative circumstances, cannot grow into a human being. It does not have the potential to.

What's the difference, again?

You're asking for the scientific difference between sperm and an embryo?

You defend one to the death and waste the other by the millions, for what purpose?

Sperm = not potential human being

Embryo = potential human being