The forum codes how images are uploaded differently. When the forum itself does it it does so as an attachment that references a link. You get a preview and then click on that to go to the image. When uploading via TapaTalk it actually does a direct link to the actual image without the preview and that is why they are different sizes.

Image uploaded thru web browser shows as a reference attachment and not a direct link to actual uploaded file
15957-DEFAULT-l.jpg

what the actual attachment location is using direct link.



Link Direct to image on internet