This approach's upside is higher performance the downside is you must choose what level of memory you desire at time of purchase, and there is no post-sale upgrade opportunity. From a practical standpoint, the crucial difference is that in the M1, memory is an explicit element of the architecture, so there are no memory slots on the system board for a M1 Mac.
Unlike Intel processors’ integrated graphics, the M1 has an embedded graphics processor shared between both the processor cores and graphics cores.
