Thats not much of a comparison there as those are two different programs using different exif programs and even different cameras which most likely write the information differently.
Photopost Pro = jhead = canon powershot
vbGallery = exif in php = Nikon Camera
You would have to use the same camera and same photo and upload it to a vbgallery and a photopost site and see the difference and then again it comes down to one uses jhead as the exif extractor and one uses php's exif function. So literally there is no comparison. The end result is we have no control over what is written to a photo and what the extractor that is used extracts or what info a camera writes to a photo.