Most lawn mowers are mains powered. This is the best choice for small to medium sized gardens. They are smaller systems, cheaper to buy and easier to store. However, check that the cord allows you to cut to the end of your garden before purchasing one. Additionally, there are the battery-powered lawnmowers that have all the benefits of an electric lawnmower without you having to worry about a cable. However, they can be more expensive than electric models due to the same battery.
Petrol lawn mowers are the best choice for large gardens where a power cord would not be suitable. They are a little more expensive but much more powerful and faster in cutting. They are also easier to maneuver around large objects. However, they will need maintenance like car engines and you will need to check and top up the oil periodically.
Push mowers are small cylinder mowers that you simply push around the lawn. They are best for small gardens and do not use electricity or produce noise and emissions. They are the most ecological choice but, unfortunately, depending on the garden, also the less practical one.
If your outdoor space is much larger, there is a whole category of motorized lawnmowers that can be driven, very similar to those used for the care of lawns in football fields or municipal parks. They require much higher costs but have the ability to travel great distances without physical effort.