"Welke kruiden gebruiken jullie?"
Translation:Which herbs do you use?
Officially it's the same difference as herbs vs. spices: "kruiden" refers to the leafy green or flowering part of a plant (e.g. basil, oregano) while "specerijen" are made from other parts (e.g. pepper, cinnamon).
But in everyday language, we often use "kruiden" to refer to any spice. It rolls off the tongue better.