The differences between 2.4 GHz and 5GHz frequencies are range and their data rate. 2.4Ghz can reach farther but offers a slower data rate. 5 GHz provides faster data rates but has less range. Therefore, 5 GHz should be used when you are close to the access point or in the same room as the wireless. Additionally, not all devices are capable of utilizing 5 GHz. 2.4 GHz is the most commonly used if you are farther away from the access point or wireless router. The best wireless frequency to use is dependent on your wireless environment, your device and your location.
Common wireless standards 802.11ac, 802.11n, 802.11g, and 802.11b:
802.11ac: The most recent wireless standard. It can operate at 5 GHz for newer 802.11ac devices while also offering 2.4 GHz 802.11n Wi-Fi for older devices. This allows for less wireless interference and a more reliable signal. In theory, it can achieve up to 866.7 Mbit/s in data transfer speed. 802.11ac was finalized in 2013.
802.11n: The previous and most popular wireless standard. Unlike modern 802.11ac, it can operate at either 5 GHz or 2.4 GHz, but not both at once — that means more interference. Theoretically, it can achieve up to 150 Mbit/s in data transfer speed. 802.11n was finalized in 2009.
802.11g: Is limited to only 2.4 GHz. 802.11g can only achieve data transfer speeds of up to 54 Mbit/s in theory. This standard was finalized in 2003.
802.11b: This standard is even older, finalized in 1999. It offers speeds up of up to 11 Mbit/s in theory.
Remember that these speeds are theoretical, and you probably won’t achieve anything nearly that fast in the real world. If you have a device that is limited 802.11g and 802.11b it is recommended that they are replaced with the newer standard device.