There are several differences with consolidation and rehab to cure a default on federal student loans. The first, and probably foremost, is timing. The rehab takes nine months, where a consolidation is only 45 days. If you're in a hurry, obviously, consolidation will be better. Consolidation is also better if we want to change someone's loan type so that we might be eligible for a better income based program or eligible for one at all, for that matter.
A rehab is a little bit better for someone's credit if you ultimately want to purchase a home because it does remove the default. The late pay stay on your credit but the default is removed, unlike a consolidation. There are some other differences as well. It's important to know those differences and pick the right option for you if you need to cure a default.