* The orange tree itself is definitely an organism. It's a living thing that grows, reproduces, and carries out all the processes necessary for life.
* The orange, while part of the tree, is not a separate organism. It's a fruit, which is the tree's way of dispersing its seeds. Fruits are essentially a combination of tissues that contain seeds, designed to be attractive to animals who will eat them and spread the seeds.
So, the orange itself isn't a living, breathing thing on its own, but it's certainly part of a living organism. It's like how your arm is part of you, but isn't its own individual organism.
