Do not confuse asparagus beans with asparagus. These are completely different plants.
But asparagus beans and string beans should be considered closer to understand how they differ and what unites them.
Asparagus beans are unripe (green) pods of green beans. But not every string bean can be called asparagus.
Beans come in different varieties. And it is grown both for grain and for a spatula - this is what the bean pod is called.
Bean shelling varieties have a coarse parchment layer and the same coarse fiber along the seam. Therefore, such beans are grown only for seeds (grain). Of course, shelling bean pods are eaten, but only completely green, unripe.
But vegetable varieties are grown just on a spatula. These include green beans of sugar varieties, which does not have a parchment layer. Such beans in the stage of technical ripeness has tender, fleshy pods. Also, sugar pods have no longitudinal fiber along the seam.
There are green beans of semi-sugar varieties. There is a parchment layer in such pods, but it is not rough, therefore, young green pods are also used as food.
The varieties of beans differ not only in the quality of the pod, but also in the shape and nature of the growth of the stem. There are climbing varieties, half-growing and bush. For example, the Harmony variety is good because it has no parchment layer, but the pods are small. And in the climbing variety Liana, the pods reach a length of 60 cm. There are also early ripening bush varieties, for example, Sacks without fiber 615. Asparagus beans - this is the vegetable beans, which are grown specifically for green pods. Recently appeared varieties of asparagus beans with long thin pods, very tender and juicy.
And it does not matter whether it is curling beans or bush. The main thing is the quality of the pod itself. Therefore, sugar varieties without parchment and fiber are appreciated.
When the asparagus bean pod breaks, you can see juicy flesh that looks more like jelly. By the way, asparagus beans often have a round section at the fault. And by this it differs from half-split beans with a flatter pod. And all the more so, it is completely different from the pod beans of shelling varieties, flat pods of which have coarse sash and coarse longitudinal fiber along the seam.
In conclusion, we can draw the following conclusion: the whole asparagus bean is a string bean, but not every string bean can be called asparagus.