In the U.S., the leaves and stems of Coriandrum sativum are called cilantro. In the UK and other parts of Europe (based on personal observation), the leaves and stems are called coriander. In the U.S., seeds are called coriander, and elsewhere they are called coriander seeds. It’s a little confusing when I’m making a recipe that calls for coriander, until I check to see where the recipe comes from.
Usually, it should be clear by how the ingredients are prepared or used. I can’t recall a recipe where I needed to check its origin to be sure.
Shouldn’t the metric measurements give you a very strong hint? Or does the UK still use cups and Fahrenheit?
Well, like here’s an example. It’s a British recipe, and they don’t even bother using different words for coriander and coriander seed. There’s 1 tsp ground coriander, and then a “handful coriander.” The former is referring to the seed, of course, and the latter the green. Usually there’s a hint with a word like “handful” or “fresh coriander” or “chopped coriander” or similar, and “ground coriander” obviously refers to the seed.
Your recipe asks for 450g carrots and 1.2 l vegetable or chicken stock - metric measurements that no self-respecting American would understand. I suspect that the British people who would follow the recipe would just go down to the local TESCO and pick up packets of “ground coriander” and “coriander”, never knowing that those come from different parts of the plant.
You think they would fail to notice that one is a spice and the other a herb?
:smack: Oh, duh. Yeah, the measurements. Well, here’s one that doesn’t have meteric measurements, although “coriander leaves” does give it away. 
(Though I’m fairly sure I’ve seen British recipes that use cups or pints and specify how many carrots rather than weight. Might be older ones, I dunno.)
Anyone who blindly picks up packets of “ground coriander” and “coriander” probably doesn’t give much thought to the distinction between a spice and a herb.