Hi,
UploaderBase is a raw uploader object which provide the properties.
and Uploader provide the basic controls : InsertButton, CancelButton etc.
Uploader only provide FileUploaded event, developer should process the file immediately.
UploadPersistedFile maintain a .File property , and this property can be used after postbacks.
UploadAttachment like the UploadPersistedFile , and it maintain multiple files.
Regards,
Terry