Sure, coriander, cinnamon, and paprika are all spices, just as thyme, rosemary, and mint are all herbs. It's amazing how often we use these herbs and spices in our cooking, and yet, have you ever really thought about why spices are spices and why herbs are herbs?
It's actually very straightforward. Once I went to the trouble of looking it up, the difference was obvious.
Herbs are the leaves of the plant, while spices come from the roots, bark, and seeds. Essentially, any part of the plant that is not a leaf and can be used for seasoning would fall into the spice category.
Some plants have both: like cilantro (the leaves) and coriander (the seeds of the cilantro plant). Some only give us one or the other. As far as I know, no one uses rosemary roots or nutmeg leaves in their cooking, though there's a first time for everything!
The herb-or-spice distinction doesn't necessarily change the way we cook with any of these seasonings, but it's a handy thing to know next time it comes up while playing Trivial Pursuit.
Related: Quick Guide to Every Herb and Spice in the Cupboard
(Images: Emma Christensen and Silk Road Spices)
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Well, I have been using this distinction to decide at what point of the cooking I should add them. Spices should go at the beginning, so the taste blends well with the other ingredients, and herbs at the end, so their taste stays fresher and better defined. Someone told me dried herbs, particularly oregano, turns bitter if cooked (fried or long boiled in a stew), but either I don't feel its bitterness or it doesn't bother me at all.
So, I try to add spices at first and herbs at the end, but truth is, I add them when I remember to.
Fresh herbs should definitely be added at the end of cooking. But some dried herbs, like bay leaves, need more cooking time to draw out their flavours, and so should be added early.
Cygne, that's a good point. I was thinking of oregano, freshly dried (does that make any sense? I mean it hasn't been dried forever) but bay leaves definitely need quite a bit to fully develop the taste and scent into the meal.