One of the original main advantages of a RISC (Reduced Instruction Set Computer) was that it used less power than a CISC (Complex Instruction Set Computer). The Intel cpu that is at the heart of most Windows and newer Mac’s is a CISC.
When the Chromebook first came out and began to sell like hot cakes some vendors were taking advantage of the RISC cpu/motherboard to sell systems with longer battery times and lower costs than the Intel/AMD-based cpus.
Intel has been designing lower power draining cpus/motherboards for laptops for years. They apparently got busy and created something for the Chromebook line(s). That is why you have Intel-based Chromebooks with 10+ hour battery times and lower costs than the RISC-based systems.