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.
If this question were to apply to conversational use of these verbs, I would definitely suggest "see", since this is the verb that gives the basest meaning; i.e. the function of the eyes. First the person sees the painting, then pays attention to it, giving rise to "looking". (Consider: "See More" buttons, underneath article snippets on the web.)
However, since we are talking about the Web, and specifically about linking to content, the most common verb for menu buttons is "View". This is the verb that has seen most use in the technology world.
I haven't been able to provide any sources for my answer, other than to say that "View" is the predominant word on the Web in this type of use case.
Best Answer
Here are some simple rules that will help deciding which word to use:
See is used as inactive word; you just see without any effort:
Look is used as active word, you make an effort to see:
Watch is also an active word; you also make an effort, but it is for a longer period of time:
Here's an example demonstrating the difference:
Back to examples:
I'm watching "Star Trek" — it is a continuous action;
Have you seen "Star Trek"? — it is a question if you ever seen it at all, or do you know about it;
It can be also formulated: Have you watched "Star Trek" all night?, and it will mean that you have spent all night watching a movie.
See also: (1), (2).