There are two kinds of railway gauge sizes on the JR group lines. They are the 1,067 mm and the 1,435 mm-wide gauges. The 1,067 mm-wide gauge is the most common. It was originally introduced by the U.K. when the first railway route was constructed between Shimbashi and Yokohama in 1872. Most of the JR group lines are this size of gauge. On the other hand, the 1,435 mm-wide gauge is adopted by the Shinkansens and two so-called Mini-Shinkansens. Needless to say, they are suitable for high speed train operations.
Most of the JR group train models are only for 1,435 mm tracks or 1,067 mm tracks, but there are exceptions. For instance, the EMU JR East 719 series is for both 1,067 and 1,435 mm-wide gauge tracks models. You can see two kinds of the 719 series at Fukushima Station in the Tohoku District. They are the 719-0 series (for the 1,067 mm-wide gauge Tohoku Main Line) and the 719-5000 series (for the 1,435 mm-wide gauge Oou Main Line, the Mini-Shinkansen). For your information, the 719 series was launched in 1989, and a total of 84 units have been built by Tokyu Sharyo and Nippon Sharyo.
On May 26th, 2016, JR East Sendai Office made a press release announcing that the EMU 719 series will be retired soon. It will be replaced by 4-car trains, named the E721-1000 series. The EMU 719 series is now an endangered species on the tracks.
EMU JR East 719-0 series (for the 1,067 mm-wide gauge track) stands at Fukushima Station
Official information about the EMU JR East 719 series (in Japanese):