Is embryo destruction worse than abortion?

Both abortion and embryo-destructive research are the unjust killing of innocent human beings, and ought to be stopped. But is one actually worse than the other? Professor Richard Stith explains:

Embryonic stem cell research ... is wholly dehumanizing. When parents turn the living human embryos they have begotten over to science, they not only forget them as children but also turn them into commodities, donate them for eventual body parts. The embryos become wholly instrumental, they become resources to be calculated and consumed. They are degraded before they are destroyed. Like human embryos created by cloning, they do not die as unwanted children, or even as human beings, but as things to be used and used up. No greater negation of human dignity is possible.

Read the rest of his argument.