Final answer:
The smaller contraceptive device similar to a diaphragm is the cervical cap, which is a barrier method of birth control used with spermicide.
Step-by-step explanation:
The contraceptive device that is similar to a diaphragm but smaller is called a cervical cap. Like the diaphragm, it is a barrier method of contraception that is inserted into the vagina to cover the cervix and block sperm from entering the uterus. The cervical cap is also typically used in conjunction with spermicide to increase its effectiveness. When used correctly, it can be an effective means of birth control, although it does not protect against sexually transmitted infections (STIs).
Examples of other barrier method types of contraception include the male condom, female condom, sponge, and spermicides, as well as more permanent solutions like sterilization.