Power is expressed in watts (W) or, more commonly, kilowatts (kW). It is a momentary value representing the intensity of the action, comparable to the speed of a vehicle or the flow of a river.
The amount of energy is expressed in Watt-hours (Wh) or kilowatt-hours (kWh). It is therefore the result of applying a power for a certain time (power x time). It is cumulative over time, like the distance a car travels (speed x time) or the amount of water flowing (flow x time). The longer the duration, the greater the quantity. It is therefore the duration and intensity of the action that determines the amount of energy.
The amount of energy is represented by your meter reading, which increases over time. It increases more quickly if the transmitted power is high (e.g. if your oven is in use) and less quickly if the power is low (when most of your electrical equipment is switched off).
You can also find out how much momentary (or instantaneous) power you are using on your smart meter. Please refer to the meter manual which you can find here.