Apologies if this has been answered - I'm reading in time order. Runner beans are about 20-30cm long, rough om the surface. You eat the pod. They're usually sliced into very thin strips, like green tagliatelle. They used to have a stringy down each side that you removed, but now most gardeners grow stringless ones. They can be tough if they're left on the plat too long, but are delicious picked before the beans inside are fully swollen.
Green beans, aka French beans, are about 15cm long and either flat or cylindrical. As with runners, you eat the pod, and these are eaten whole, unsliced. They should not be stringy or tough or spiky. Frozen ones are a bit meh but ones you grow yourself are wonderful.
Different varieties of French beans are left to mature on the plant, and the ripe seeds are, depending on variety, pinto, flageolet, kidney beans, Heinz baked beans, etc.
Broad beans are the same length as French beans but much fatter. The pods are fur-lined, and you eat just the beans. Again, they need to be picke
d young, before the bit holding the bean into the pod has turned black.. Some recipe books tell you to remove the outer skin of the bean. Life is too short