What's the better option? I don't know what the numbers mean so if you can help, please do it.
DDR3-1600MHz CL9 is superior than DDR3-1333MHz CL9. The first number in the following series represent the CAS Latency: 9-9-9-28
DDR3-1600MHz has a faster memory frequency, higher memory bandwidth and moreover less CL9 which denotes the memory is faster. Usually, lower the CL faster the memory. For a DDR3-1333MHz memory the CL is on the higher side, usually it is something around CL5 or CL6 for 1333MHz. So definitely 1600MHz considering the specs. Hope that helps.