There could be major differences but you're a little vague on the details.
These are the likeliest of differences between the two product lines:
1. Quality of construction: How long do you want to own this thing before expecting ... say the handle to fall off? And remember this! You don't want the handle to fall off while the kettle while your pouring the water into the cup while the kettle is full of boiling hot water.
2. Time in boiling: The more expensive kettle, if designed well with its design more based on research and basic physics of thermodynamics, should boil quicker and more evenly then the cheap kettle using materials that flawed and impurities that are thermodynamic obstacles if time is an issue.
3. There could be simply aesthetic differences that separate the two.
4. Form and function: the more expensive one might have an innovation that might make it more appealing in terms of ease of use.