Power and energy. The encyclopedia says (I'm not pretending to remember my school physics) that power is the rate of doing work or using energy, it can be mechanical or electrical, and it's measured in kilowatts. Energy is the capacity of a body or substance for doing work, and it can take the form of heat, light, sound, mechanical or electrical energy. Electrical energy is measured in kilowatt-hours.

Cars are more or less powerful, depending on their engine output. Talking about people, having power means having a lot of authority, whereas having energy means being very active, always working or playing, never being tired. In English, power stations or power plants generate electricity, and at home we use the word power for electricity, like "Is the power on?", but we try to save energy in heating and using electricity. In English, PEOPLE are energetic (full of energy); ČEZ is a power (electricity) generating company.