The core difference between 120W and 240W USB-C cables is the maximum power they can carry and the internal build required to support it. At 240W, thicker copper conductors and a more capable e-marker chip are required, which is why these cables tend to be slightly thicker and more expensive.
In everyday use, most smartphones draw well under 65W, so a 120W-rated cable is more than enough for nearly every phone and tablet. A 240W cable earns its keep with devices that genuinely need that much power, such as high-performance laptops, gaming notebooks, and external monitors.
Using a 240W cable to charge a 65W phone will not cause any harm; the PD negotiation between cable and device automatically sets power to whatever is actually needed. In other words, a higher wattage rating does not automatically mean faster charging, the device's own maximum input is what actually matters.
Charjett's CJ-120 and CJ-240 models reflect exactly this split: the CJ-120 is optimized for daily phone and tablet use, while the CJ-240 targets laptops and professional equipment that need serious power. Picking the right one is a smart call for both performance and budget.