What is the difference between gas and electric fireplaces?

An electric fireplace has a heating element powered by electricity that generates heat where as a traditional gas fireplace uses some sort of fuel and produces heat output via combustion. Gas fireplace provides a realistic look with quickly heat up the space with real flame but comes with higher up front cost, complex installation and safety issues. Electric fireplaces have lower up-front cost but running costs are higher and the simulated flame does not provide a realistic look even though the flame ambience can be created even if heat is not required.