Praise is when you tell your child that they've done something well or behaved in positive ways. For example, 'Great job, Riley', 'Well done, Jo' or 'That's awesome, AB'.
Descriptive praise is when you tell your child exactly what it is that they've done well. For example, 'I like the way you've found a spot for everything in your room'. It's also more genuine than non-specific praise like 'You're a good boy'.