Indeed. You will see some things marked as 220, some as 230, some as 240. Reason being, 220v used to be the standard, but then the grid reached capacity. Power (watts) is voltage times amperage. Wires have a maximum amount of current (amperage) you can run through them for a given size (And temp rise, etc etc), so in order to increase the total power that could be delivered they increased the voltage a hair to 230v. Most devices and equipment are fine with +/-10%, so that was no big deal. Then some years later, the limit was reached again, and so the standard was increased again to 240V.
The current 240V is usually allowed a +/- 5% as well, so really it could be as high as 253V. I find my power comes in around 248-252V, so they're getting everything they can out of it. Modern equipment is designed with this in mind and is fine. My older machines want 220 or 230V though, so I run a pair of buck/boost transformers to reduce the input voltage to their nominal input voltage. Might be fine, but for a couple hundred bucks it gives me peace of mind.
When in doubt, the multimeter is your friend.
You can also sometimes ask the power company to adjust the transformer on the pole, and sometimes your machines may even have built in transformers to account for this (My HAAS mills do).