Was ist der Unterschied zwischen try this pizza und try out this pizza ?Du kannst auch einfach Beispielsätze geben.

There is no difference in this context. :)
"Try" and "Try out" sometimes have the same meaning, which just means to "try". It's mostly related to food, or related to a recommendation someone has made.
For example:
"Hey, John! Come try out this new restaurant with me tonight!"
"Mary, did you try out that new sandwich shop I told you about? It's really good!"
"My grandmother told me to rub medicine on my wounded leg, so I tried it out."

"Try out" can also mean "to attempt qualify".
For example:
"I tried out for the Olympics, but I was not fast enough."
"I tried out for joining the basketball team, I hope I made it!"
"Try-outs are this weekend, I'm going to try to join the choir team!"

I hope this helps. :)