Benchmark it and tell me. The truth is that most RPis are made using older process nodes to reduce costs. Laptops are often made using the best avaliable process node and core design. A modern raspberry pi 5 uses a 16nm processor with Cortex-A76 design from 2018. A laptop in 2015 would be using 14nm Broadwell processors from Intel. This was a time when 15W U series processors were gaining popularity, so sustained load power consumption is quite low. A 2015 laptop is 10 years old, and wouldn't run Windows 11, so will be ewaste this year. Same with a lot of 8 year old machines actually.