Actually, even the most benign birth control pills act by keeping an already fertilized egg from attaching to the wall of the womb and being carried to term. Therefore, they are abortion inducing drugs. This information is clear in the bed sheet sized paper included with birth control pills, or at least used to be included with them.
Spermicide foam and other spermicides act by actually killing sperm cells thereby ensuring that no egg is fertilized. Big difference.