When I have an array which comprises both strings and integers , then applying the sort function in below mentioned ways , gives different output. Could anyone please explain me on what basis the sorting is happening in the following two cases :

@arr = ("jack", 80, "martin", 3, "allan", 'george');


@sort = sort { $a cmp $b } @arr;

print "@sort \n";
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output :
3 80 allan george jack martin

If the sort function is changed to

@sort = sort { $a <=> $b } @arr ;
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then the output changes to
jack martin allan george 3 80