That Marathon record is seriously impressive, he didn't just beat it, he smashed it.
For the decathlon I honestly don't know what the record means in that context because it's so subjective.
Are all of those achievements really exactly the same difficulty? I genuinely don't know but if you put the world records in each event into a calculator it suggests that the running events (110 hurdles and 400 in particular) are massively undervalued.