There's a lot going on in this picture. We were sure the differences would be in some tiny underwater bubble, but we were very wrong. They're quite obvious when you finally locate them. Spongebob's nautical themed hat was the first thing we saw. In the first image his hat features an anchor, while in the second one it has changed to a snowflake. We think the anchor is more his style.
The ketchup top is another pretty easy one. In the first image it's red and in the second image it's green. Now, for the third difference, we don't actually know how to describe it. It's some kind of special flower that appears in the second image but isn't there in the first one. It even has a little plate that it's resting on during the juggling process.