gigawatt thermal vs gigawatt electric is the distinction between a power plant's raw heat output, measured in gigawatts thermal (GWth), and the electricity it actually delivers to the grid, measured in gigawatts electric (GWe), after the losses of converting heat into power.
Every thermal power plant — coal, fission, or 📝fusion — makes heat first and electricity second, and conversion through a steam or other turbine cycle typically keeps only 30 to 45 percent of the thermal power. One gigawatt thermal therefore yields a few hundred megawatts electric, and quoting one number where the other is meant inflates a plant's promise by a factor of two to three. The distinction is essential for reading fusion milestones: headline fusion power figures are thermal — 📝ITER is designed to produce 500 megawatts of fusion power but will convert none of it to electricity — and a plant's own systems consume part of what it generates, so net electric output shrinks further, the gap that 📝Q_plasma vs Q_engineering accounting makes explicit.
Commercial designs are specified in electric terms, because electricity is the product a plant sells. 📝ARC is designed to deliver about 400 megawatts of electricity to the grid — the number that matters to a utility, whatever the thermal power behind it.