Question

is 2 : 5 same as 5 : 8

Answer 1

no it is not the same.
because
2:5 is not the simplest form 5:8.

Answer 2

well it's not just same 
evidence :
2:5 is nothing but 4:10 or 6:15 or so on
but 5:8 adds on uptill like 10:16 , 15:24 etc.

both the ratios are equal only when they're equalateral