The site won't take a JPEG which is what my "good" camera generates but will take the JPG that my phone generates. I can convert it in Photshop but is there a real difference?
JPEG vs JPG
Basically same file type.
Just edit your images file name, by changing the extension. No other action or conversion required.
EXAMPLE
change filename from photo.jpeg to photo.jpg
If you want to dig into history; see this link....
https://stackoverflow.com/questions/23424399/jpg-vs-jpeg-image-formats
John