Watts are a measure of power, which is a rate of doing work. All of these devices consume power.
In the case of the lawn edger/trimmer, the voltage rating tells you what type of battery pack you need to put in it. That’s important to know if it comes without a battery pack, or if you need to replace the pack. Also, generally speaking, the higher the voltage rating, the more powerful the edger will be. This isn’t a law of physics - it would be possible to make a weak edger that runs on high voltage - but no company would do this. A higher voltage requires a battery pack with more cells in it, which is more expensive, so why do this if you don’t get more power out of it? Also, the number of watts a battery-powered device can draw depends on the condition of the battery (a new, freshly charged battery can produce more power than an old, partially discharged battery).
In the case of the snowthrower, it’s important to know how much current it draws (i.e. amps) if you’re going to plug it into an electrical outlet. If the outlet is on a 15 amp circuit along with, say, a microwave oven, running both at the same time will blow the circuit breaker. Also, if you’re going to use an extension cord, it’s important for the cord to be rated to carry enough current for the snowthrower. If you use a 13.5 amp snowthrower with an extension cord that’s rated for 10 amps, you could overheat the cord.
Also, for devices that run on household current, the power is approximately the current rating times 120 (which is the voltage of the outlet). So the snowthrower in question will draw around 1,620 watts. That doesn’t mean it will produce that much power at the business end, because nothing is 100% efficient (some of the power will be wasted as heat). Also, there’s something called the “power factor” that I won’t go into here.
Things you plug into household power outlets in the U.S. always run on 120 volts, which is the standard household voltage in this country. There’s no reason for a manufacturer to put this on the box.
The LED lightbulbs are rated in watts because that’s directly related to how much light they produce. It’s not really important to know how many amps it draws, because it’s so low that it should never trip a circuit breaker (for a 13 watt bulb it’s about 0.11 amps). Most LED lights are also rated in lumens (i.e. how much light they put out), and in the wattage an incandescent bulb would draw to produce the same output.
BTW, LED bulbs are rated in watts, not watts per hour. A watt is a rate of energy usage or production (it’s defined as one joule per second, where a joule is a unit of energy). A watt per hour would be one joule per second per hour, which doesn’t make sense in most situations.