To appreciate something is to be happy or glad for its existence. To admire something is to enjoy something in a person or thing that has some qualities that you hold in high regard. Let me try to explain.
I appreciate that I have a job. I appreciate that I have good health. I appreciate that my car is still running after 120,000 miles :). I would not say I admire any of these things as I am happy simply only for their existence.
I admire someone who is always honest. I admire intelligence in a person. I admire the size of the universe.
Usually, admiration (or admiring something) means that you are looking upon its qualities as things that you value. Often we admire things that we wish we could be/have.
So, I guess to appreciate the scenery would be to enjoy that it exists and be happy merely being present within it. To admire the scenery would indicate that we might gaze upon it longingly (with great desire to be in it all the time)
The two can be very similar but at the same time...different.
Hope that helps.