You can contribute to both, and when your child is ready to attend college, as colleges do accept payments from both. There are some features and benefits that may make one account more favorable than the other.
For instance, the Coverdell education savings account (formerly Education IRA) may be used for education costs for private school, kindergarten through grade 12, and for higher education. The 529 plan assets may be used for higher education expenses only.
(For further reading on this topic, see Choosing The Right Type Of 529 Plan, Investing In Your Child's Education and Don't Forget The Kids: Save For Their Education And Retirement.)
This question was answered by Denise Appleby