Two terms for "According to" - What are the differences between 根据 and 按照?
根据 is more formal, and preferably used when speaking about doing something according to some serious guidelines. Like following a law.

按照 is less formal, and can be used when doing something according to some less serious guide. Like following a person's idea.

Examples

根据新法律上的规定，小学老师都必须..
In accordance with the new law, all elementary school teachers must...

按照我们家的习惯，晚上九点钟小孩要去睡觉。
At our home we are accustomed that kids go to sleep at 9pm.