Earlier quoted context omitted.
You'll get similar battery life only if the Intel gets severely power limited. A newer AMD would be more comparable.
If you scroll down on the link above you can see some graphs that show the 1280P is significantly faster than the M1 and the battery lives are very similar 11 hours vs 13 hours. AMD are also doing a good job. The 7000s look very good. Crazy that this is still on a larger process node than Apple.
The Intel is fast only with a ridiculous power usage, thus low runtime. It comes nowhere close to the M1's runtime when forced to the same high load.