FireWire, also known as IEEE 1394, is not a cable that you normally find today. Popularized in the early '90s, it has long been the competing standard for USB, no different from today's Thunderbolt. FireWire offers much faster speeds and is even faster than USB 2.0. A connection commonly found on older external hard drives and digital cameras.
FireWire 800 Vs. they are not backward compatible. They do not even look the same from afar, which can cause confusion. The older standard FireWire 400 is a flatter port with a rounded side and the faster version 800 is similar to a fat USB port.
However, the naming scheme is accurate as it represents the actual speed of the cable: 400 Mbps vs. 800 Mbps. By comparison, USB 2.0 is 480 MBit / s and USB 3.0 completely exceeds it at 5 Gbit / s.
Get a dongle
Unfortunately, FireWire nowadays requires a FireWire-to-2018 adapter as much as you need the actual cable. Some adapters can be found on Amazon. Make sure it's the correct FireWire type because it's incompatible.
You should also avoid a USB 2.0 adapter if you want to connect FireWire 800, as it will be much slower. However, if that's the only way you can connect, it's not bad running at half speed.