Photoshop JPEG vs JPEG2000

[MemaJoy]

When I try to save in JPEG, sometimes only JPEG2000 comes up and I then have to work around it to bring up JPEG. What is the difference between the two. I notice the file size is a lot smaller in JPEG2000. Is this because it is deleting information? I am really confused.

[lambiloon]

Hi jpeg is latest one and working in all device jpeg2000 is old one and most compatible...regards

[J453]

Can you post a screen shot of the save dialog where JPEG 2000 is available and JPEG is not?