In North America, there are two cords that come with the tools, as has been stated. One is 16 AWG and the other is 18 AWG. In every other way they are virtually the same, both are SJO cord and feel similar, though the 16 AWG cord is slightly bigger diameter - it has more copper.
The biggest difference that is noticeable to the user is that the smaller, lower ampacity, 18 AWG cord, (490649), has an extra protrusion on the male part of where it plugs into the tool. The corresponding female part on the tool connector has a depression that is designed to receive that protrusion. The higher ampacity, 16 AWG cord, (490656), has a flat and the corresponding female part on the tool connector has no depression, but rather has a flat. This is designed so that the lower ampacity cord can't be plugged in to a tool that draws more current than the cord was designed to supply.
For the safety of all involved, at least the safety of the tools' Plug-It connections, please don't be tempted to accidentally remove the little protrusion on the lower ampacity cords.
Tom