CPC is the cost per click advertisers are paying. PPC is the amount of competition from 0-1, 1 being the highest. So if a keyword has a CPC of $2.00 and a PPC of .85 it means advertisers are paying about $2.00 per click for their ads and the amount of advertising competition is fairly high for that keyword. If the PPC was .25 it would mean the advertising competition is fairly low for that keyword. Keep in mind that is advertising competition and not SEO competition.