Spacers tend to hurt more than the actual braces because spacers are placed in between the teeth to make room for the metal rings, which are attached to the teeth. The pain of having spacers placed lasts for a couple of days.
Not everyone who needs braces has spacers beforehand. After a week of having the spacers in place, the teeth are now ready for the braces. Installing the braces does not hurt. However, the pain and discomfort start when the orthodontist starts adjusting the braces. The pain goes away quickly, and being able to eat comfortably returns in a few days.