thats kinda true, but still not.
higher number means better perfomance within a series/generations.
For example 440 is better than 430.
But let's say that 520 is about at the same perfomance as 420(if it even exists). The 520 is just in a newer generation, and is somewhat a bit better than the 420(e.g. lower power consumption, or less heat), but is still for the people who don't have much money, or just use their computer for low perfomance tasks, thats what we call entry level.
this is not always true, I can't really explain how these things work, if you'd like to understand it, you should check reviews, benchmarks and so on.