In 2019, nuclear power produced 10% of the global electricity used worldwide. Natural gas provided 24% of the global electricity consumption in 2019. Both are very expensive, non-renewable fossil fuels.
The difference is that nuclear power can only produce electricity, whereas natural gas can also be used to heat buildings, and serve as a combustion to cook, and for cars, ships, and aeroplanes.
There is much concern about nuclear power and natural gas because the European Union plans to accept these as green energy sources to combat climate change. From whatever perspective we judge nuclear power and natural gas, they are all but green.