Comparison between values from two distributions

Hi there. I need your help. I have two distributions and I want to compare them in 2 ways. I think an example would better explain my purposes:

Let's make an example. Let's say I have the trends for oil and diamonds price over 5 years, from 2002 to 2007. I have two vectors, one for diamond prices over 5 years, and one from oil prices over the same period. I now want to compare the prices in the year 2005. I want to do that within the same distribution (so, to see if the diamond price in 2005 was different from diamond prices of the other years) and between the two distributions (so, to see if diamond price and oil price in 2005 are different with each other).

I'm pretty noob in statistics, as I guess you noticed by reading this post. But please help me, so I can improve. Thanks a lot!