MacBook had much faster Processor, Chromebook Pixel use UltraLow Voltage CPU which tends to have much lower TDP and much less sustained clock. In this case 2.2GHz for Chromebook vs 2.7Ghz for MacBook.
Cpuboss gives the edge to the i7, but if you have some source with benchmarks comparing the two CPUs (or similar ones) I would be really interested in seeing them, in particular how TDP affects performance.
In my opinion the recently refreshed 13´Macbook Pro is one of the most interesting machines on the market, for the price.