webclient upload file methods

It seems that webclient supports PUT and POST uploading. Is there any difference?

Yes, one sends a PUT to the server, one sends a POST. In theory, PUT means "enclosed entity [should] be stored under the supplied Request-URI", and POST means "the entity enclosed in the request [i]s a new subordinate of the resource identified by the Request-URI"

But in practice, it's up to the server what to do.