Fast.com specifically measures your speed to a Netflix mirror, vs CloudFlare measuring your speed to a CloudFlare data center. Netflix probably has a box in your ISPs data center/head end that is closer to you (unless you live in a town with a CloudFlare data center, in which case the difference shouldn't be this drastic).

CF's score is probably more relevant since there's a lot more sites that are hosted there than netflix (which is just netflix).