Hi Dinghui. They are very close but this is what Macmillan dictionary says about the difference. wilt 1 verb wilt if a plant wilts, it gradually bends towards the ground because it needs water or is dying wither 2 verb wither if plants or flowers wither, they become drier and start to die So wither is not necessarily because of weather.

Wilt has the connotation of bending, falling, collapsing. Whither has the connotation of shriveling, drying up, wrinkling.

They are close in meaning, but subtly different. Sometimes they could be used to describe the same thing. But wilt has more of an immediate sense to it, like something that is happening now or just happened recently, whereas wither has more of a sense of something that happens over a greater period of time. You can use wilt for people, too, in the common expression that someone "wilts under pressure", that is they become weak or tired or less confident under the pressure of something like a job interview or a test or giving a speech in front of many people.

We say flowers wilt. That’s when they are no longer fresh and their petals start wrinkling and losing their shape. I think leaves of a tree can also wilt. Wither means when something slowly loses the material it is made of trending towards being nothing. A person may wither away (losing all of their energy and muscle) and die. I think any living thing can wither away. But maybe only plants can wilt. I’m not 100% sure that’s right but I think it’s close.

they are essentially synonyms, i dont think there's much difference