The CPU is the "brains" of the laptop since it does all the calculations.
The chipset basically determine what type of hardware the laptop can use. For example, it is the chipset that determines if the laptop can support USB 3.0, USB-C and Thunderbolt 3.
The lines have blurred over the past several years though. For example, the memory controller used to part of the chipset, but it has been integrated into the CPU. The memory controller determines what kind of RAM the CPU is able to use like DDR2 and DDR3 RAM. Integrated graphics used to be included in the chipset, but with the release of the 2nd generation "Sandy Bridge" Intel CPUs in 2011 the graphics core has been integrated in the CPU.