You are correct - with an i5 CPU, without OCing you will not get your RAM to run faster than 1333 MHz. Even if you could, outside of benchmarks the noticable difference is debatable. Could you run CL 7 16000 RAM with tighter timings if held to 1333 MHz? Maybe. And there's nothing to say you couldn't try to run CL7 1333 rated RAM with tighter timings. But in either case the difference would likely not be noticable.
Both are already very fast. The 1333 MHz RAM is $5 cheaper, and holds a slight edge. So for my money, if choosing between these two, I would go with the 1333 RAM.
Here are a couple articles you may want to read to see how similar RAM at marginal timings performs: http://www.tomshardware.com/reviews/core-i7-870-1156,2482.htmlhttp://www.tomshardware.com/reviews/ddr3-4gb-p55,2462.html