Preventable ozone layer deterioration is caused primarily by released CFCs and HCFCs. Laws were passed and enforced worldwide during the 1990s. In the US, we have the federal Clean Air Act, which is enforced by the EPA. Since then, the ozone layer situation is (mostly) under control.
Global warming is entirely different. It's a documented effect: the world's average temperture is going up, and although there is a global cooling/warming cycle, there is sufficient evidence that the activities of humans are influencing the cycle in a perturbing way. Carbon emmissions and other factors are very possible culprits.
"Third world" countries are the industrial workhorses of the world now. Any action to limit carbon emmisions is likely to affect those nations more than the rest of the world. This is why the Kyoto Protocol, for instance, sets different standards for different countries.
My contemporary took the bizzarre opinion that the Western powers fabricated it all just so that ways the "third world countries" could... I don't know, produce less? It makes less and less sense the more you think about it.