Range extenders commonly come in two form factors: devices designed to sit on a shelf or mount on a wall like a wireless access point or router, and those that mount directly on a power outlet. Both form factors offer some basic functionality that you can expect to find on any range extender. Antennas for the wireless network can be either internal or external, though external antennas can be expected to provide better signal. LED indicators are usually made available in order to be able to see the status of your network connectivity or provide other troubleshooting information.
Most range extenders designed to sit on a shelf offer connectivity for wired devices in the form of four or five gigabit Ethernet ports. Additionally, many of these devices provide a USB port to accommodate storage for file sharing or media server purposes, or even the option to share a USB printer on your network. Because of their size, these range extenders often provide increased performance over their outlet-mounted cousins through more robust processors or higher-powered amplifiers.
Outlet-mounted range extenders are often smaller in order to reduce weight and not place stress on the outlet. Because of size restrictions, these range extenders usually offer only one Ethernet port for wired devices and no USB port, and may not have the same performance capabilities as larger shelf-mounted units. What they give up in performance and capability they make up for in convenience. They're perfect for placing in a closet, hallway or behind furniture.