What are the differences? Are there specific uses for each? For my first batch of peppermint bark, I used an old bottle of McCormick peppermint extract. It turned out quite well, but I thought the peppermint flavor could have been better. I visited Penzey's and unfortunately, they don't have any peppermint extract. So I bought organic peppermint flavor from Whole Foods. It has a more viscous consistency than extract, but I think I actually preferred the flavor from the extract (or perhaps I needed to use more of the peppermint flavor). I also have some peppermint oil and am wondering how that would work in the bark.