It's not as different as the marketing would like you to think. In fact, for the low-end models even the bandwidth/speed isn't as big of a deal as they make it out to be, especially considering that bandwidth has to be shared for the GPU needs.
And if you go up in specs the bandwidth of Apple silicon has to be compared to the bandwidth of a combo with dedicated GPU. The bandwidth of dedicated GPUs is very high and usually higher than what Apple Silicon gives you if you consider the RAM bandwidth for the CPU.
It's a bit more complicated but that's marketing for you. When it comes to speed Apple RAM isn't faster than what can be found in high-end laptops (or desktops for that matter).
And if you go up in specs the bandwidth of Apple silicon has to be compared to the bandwidth of a combo with dedicated GPU. The bandwidth of dedicated GPUs is very high and usually higher than what Apple Silicon gives you if you consider the RAM bandwidth for the CPU.
It's a bit more complicated but that's marketing for you. When it comes to speed Apple RAM isn't faster than what can be found in high-end laptops (or desktops for that matter).