The 240-120 voltage problem can be remedied by using transformers but that doesn't negate the frequency difference between grids. Australia operates on 230v @ 50Hz while the US works with 120V @ 60Hz for instance, as certain electronics that are singular voltage (Hair Dryers, Desk Fans or Electric Blankets) have their frequencies disclosed even if the voltage on those are different than the one that country uses.
Does plugging in a device that has 120v-60Hz via a transformer on a grid that operates on 230v-50Hz ruin the device due to either heating elements or motors inside? Even between countries that work with 220-40v but one uses 50Hz while the other uses 60Hz, does that render those electronics (like dehumidifiers, power drills, curling irons) incompatible despite them using similar voltage (like 220v vs 230v)?
From my experience, if the device is not designed to handle the frequency in question, it matters to some degree.
I tried using a 60Hz hair clipper in a 50Hz country, it ran but it was LOUD and vibrated harder is the easiest example I can explain in practical effects.
Most things are going to be weird, not work correctly, or fail prematurely if they aren't rated for the grid freq. You can buy devices that convert for you but they're heavy and expensive and electrically inefficient because they have to invert the power to DC and then back into an AC voltage with a different frequency.
On the more technical side, the things that care the most are definitely motors, and resistive loads less so but still yes.
60 > 50, your motor will spin about 17% slower, which can cause strange effects but also your current will increase so you get a lot of effects of stuff getting hot and breaking faster.
50 > 60 your motor will spin 20% faster which will mess a bunch of stuff up also. Might work for a bit ok but then you'll start losing bearings and so on.
For resistive loads like a light or heating element then it'll pull more or less current than it's used to, which is why another poster in the thread talked about an oven burning their food or something.
Also anything that uses the grid freq as a timer, which is most things with any kind of timer built in, will not time things correctly.
To answer your question: it's usually safer, better, and cheaper to buy new stuff that matches the grid frequency vs buying a frequency transformer but it depends on your specific situation.
Short vacation? You might be able to get away with sending it, but your stuff will have unexpected results, might be unsafe, and could break. Like, I would be very cautious of a curling iron or hair dryer, common stuff people travel with. Electric blankets NO, because fires. If it's a work trip just get the right stuff for where you're going or a transformer if you have a lot of expensive, specialized equipment.
Umm, are you sure about that? If it's purely resistive, I would have thought that the frequency does not matter at all. It could even be DC. Or did someone revoke Ohm's law, or smuggle a frequency into it?
You're not wrong and my statement wasn't truly accurate, I was simplifying a bit because OP probably isn't well read on frequency dependent reactance, ballasts, LED drivers, etc. It's pretty rare to have purely resistive devices these days.
Most modern "resistive" devices actually have more complicated circuitry or mechanisms that makes frequency relevant. I guess saying current changes was probably a bridge too far, but I was trying to translate into layman.
For example, a PURELY resistive space heater that just cycles on/off until a temp limit is hit will not be affected, but most have fans and are designed to transfer heat under specific conditions. Depending on how they measure heat the coils can overheat or pieces can melt.
A simple incandescent light will act the same regardless of freq, but anything with a ballast or driver likely wouldn't, if it wasn't dual rated. Most are, but really cheap/old ones often aren't. They might flicker or burn out, burn brighter, etc.
Either way, stuff will likely act weird. Might be minimal effect or none for certain simple things but it's not recommended.
For lower powered devices, you can use a power inverter and power supply to convert the frequency and voltage. They are not particularly expensive or heavy, but it will still be inefficient since you're stepping down to 12V DC and back up to 120V or 230V AC.