Watts are a means of measuring the amount of power that's put into the motor. However, because the output power or suction you receive at the end of the hose depends on the vacuum's design and efficiency, air watts, which measure the output power and suction, are considered a better means of comparison for vacuum cleaners. Remember however, a clogged filter will quickly impair ait watt performance.
An upright vacuum cleaner has a vertical dustbin. In contrast, a cylinder vacuum cleaner has an almost horizontally positioned dustbin. Unknown to some, these two styles of vacuum cleaners offer both advantages and disadvantages. You should base your overall choice on the area you will be vacuuming and your individual preferences.
Wattage is an important consideration because motor power alone does not guarantee better suction: it depends on the overall design of the unit. If a vacuum cleaner has a high wattage, the motor is more powerful.