WiFi doesn't really have a concept of discoverability, in fact it is designed for a totally different purpose than Bluetooth. Bluetooth is usually intended for pairing two devices for short-range communication, which is why they need to discover each other. WiFi creates an entire Ethernet network, just without the wires. Most people use a wireless router and connect all other devices to that, but you can create something called an ad-hoc WiFi network between two other devices. This is difficult, and I don't fully understand it myself.