https://www.imec-int.com/en/articles/how-power-chips-backsid... has some explanation that's a bit beyond ELI5, but they have 2 pictures:

frontside: https://www.imec-int.com/_next/image?url=%2Fsites%2Fdefault%...

backside: https://www.imec-int.com/_next/image?url=%2Fsites%2Fdefault%...

Another graphic samsung used: https://www.thelec.net/news/photo/202210/4238_4577_1152.jpg

From https://www.tomshardware.com/pc-components/cpus/samsung-to-i...

> Typically, backside power delivery enables thicker, lower-resistance wires, which can deliver more power to enable higher performance and save power. Samsung's paper noted a 9.2% reduction in wiring length, enhancing performance