What is the difference between the check engine light and service engine soon light?

The Check Engine light comes on when the ECU detects something is wrong with the emissions system on the vehicle. You will need to have the ECU scanned with an OBD2 scan tool. The Maintenance Required light comes on to alert you to the fact that some scheduled maintenance, as outlined in your owners manual, is due. It can be as simple as an oil change or can be something else. Look in your owners manual to find out what service is needed.