Cortex A15 vs A73 speed Odroid XU4(A15 1,8GHz) vs Hikey 960(A73 2,4GHz)

I did some benchmark Odroid XU4(A15 1,8GHz) vs Hikey 960(A73 2,4GHz) 
discuss.96boards.org/.../2140
And I would expect better results
but it looks like it is pretty much same if we have A15 on same frequency

Anybody can explain this?

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