In this case, it is meant literally, because the motorcycle DID fall from the sky. But more often, "out of the air" is meant figuratively, in the sense of "from a random place."
The difference between the two phrases is that both can be used in the literal sense (to look in the specified direction), "look to" and "look up to" also have a figurative meaning.
The literal meaning:
Look at that, Henry's taking his first steps!
Look to your left and your right before crossing the street!
Look up at the sky, it's Superman!
Look up to your right, there's a green bird at the very top of that tree!
In all of these sentences, "look [x]" is being used to mean "look in the direction specified." This is the literal meaning of the phrases.
However "look to" and "look up to" also have figurative meanings. You can say you "look to" someone to find answers or advice, for example:
In her first few weeks on the job, Monica often looked to her boss for guidance.
This doesn't mean that she literally looked at him, but that she went to him for advice when necessary.
"Look up to" also has a figurative meaning. To look up to someone is to see them as a role model, or to view their behavior as a higher standard which you would like to achieve.
Tommy had always looked up to his baseball coach. He was tough but fair, and taught the team a lot. Tommy had wanted to be just like his coach when he was a kid.
Best Answer
This has been asked before on ELU, where what I think is the best answer says...
I wouldn't make too much of that italicised distinction though. Note these usage figures...
...where I doubt it would make any real difference if every single usage were reversed.
However, there's at least one context where idiomatically the two words are not at all interchangeable. That's when stare is used to mean gawp, rubberneck, goggle (stare openly in a stupid or rude manner).
Suppose, for example, in the supermarket with your child, you're behind wheelchair-bound paraplegic Stephen Hawking in the checkout queue. Your child may well be fascinated, but what you say is...