How much difference, ressourcewise, is there between the two versions?
Also what's version would you reccomend? 12.04 or 12.10?
You ask two different questions, I'll address the 12.04 vs 12.10 here. In a very subjective way, because it is a subjective issue.
12.04 is the LTS (long term support) version. I have excellent experience with LTS Ubuntu; my main workstation runs 10.04 LTS and I still do not see a reason to upgrade. Personally, I opt for 12.04. I'm old, and the time flows very quickly; I remember installing 10.04 as if it was yesterday. I don't want to fiddle with installations too often.
12.10 will soon be replaced by another Ubuntu version, and will not be supported in the long run. However, it features all what is new and shiny, including web apps and commercials from Amazon.