240v is two hots together.
The transformer at the pole typically converts 7,200 volts to 240 volts but the secondary winding has a centre tap (the neutral), so from that tap to one of the two hots it's 120v. That tap is also the ground (but at the panel it's split off). Your panel is split in a way where every second breaker is one leg (one of the hots) and the others are the other leg, so for 240 you would use a double pole breaker vs 120 you pick a leg then go to neutral. Hope this makes sense.
One advantage of going 240 is there is less amperage to get the same wattage so in theory the wire from the panel to the equipment will get half as hot. Keep in mind this is a very minor amount of heat that you can't really feel.
One downside of going 240v is having to find a UPS that will work with that as consumer ones you will find in the store will be 120v in and out.