In my experience the conversion has always been better for CPC traffic. This would suggest to me that the keywords you are using in your CPC advertising are too broad. People are clicking your broad adverts only to find you do not have exactly what they want. Try using more specific keywords and also 2-3 word combinations - I think you'll get better results.
It would probably be worth you looking at your logs and looking at the keywords that people are searching for and then including these into your CPC program.
The reverse is also true - you may find you're picking up searches for unwanted keywords - so you can add negative keywords too.
Many variables one needs to consider here. An important one is brand. Is this your item exclusively and do you have previous marketing into your brand. We have been around some 25 years and make an exclusive product. Although other online stores sell our product the do not rank well in the search engines nor do they attempt to give but the most basic of information. So a number of people who are already customers of our brand come to us to buy because of past experience. Our CPC conversation is ½ to ¾ percent. Our Organic is 3-4%