The difference is that having a college degree is a more-and-more important requirement for basically everyone not wanting a blue-collar job. Programmer is just one career choice out of many.
So, yes, the first example is an example of discrimination (possibly non-intentional), while the second could be caused by choices (there are probably other industries where there are many more women than there are men).
> The difference is that having a college degree is a more-and-more important requirement for basically everyone not wanting a blue-collar job.
I hesitantly suggest that of the people who choose to go into blue-collar work, most are men.
(Of the people who go into blue-collar work not because that is what they want but rather because that is simply where their life takes them, I would expect more balanced numbers. I don't have any numbers at all to support any of this.)
So, yes, the first example is an example of discrimination (possibly non-intentional), while the second could be caused by choices (there are probably other industries where there are many more women than there are men).