Monero uses Cryptonight instead of SHA-2. There are currently no ASICs available for Cryptonight, which was designed to diminish the performance gap between CPUs, GPUs, and ASICs by demanding comparatively large amounts of memory (which are commonly available in today's PCs but very expensive to have in ASICs). This means that CPU mining is still possible, whereas in Bitcoin, CPU mining is utterly pointless. The hope is that this will encourage people to mine with existing computers, preventing too much centralization, like we see in Bitcoin with a few Chinese pools having the majority of Bitcoin hash rate.