There are plenty of reviews/benchmarks out there for PCIe and SATA SSDs, just look at a couple and compare. Long story short, PCIe is faster in benchmarks and certain applications (sometimes quite significantly), but probably won't be noticeably faster than a good SATA drive in normal consumer use.
As an aside, it 32 Gb/s and 6 Gb/s for PCIe and SATA III respectively. Lower case 'b' means bit, whereas uppercase 'B' means byte. One byte is eight bits.