There are Pisceans and there are Pisceans. As with all signs, you'll encounter many different individuals, with their own quirks.
Some of the key differences between Virgo and Pisces stem from one being a 'personal' and the other a 'trans-personal' sign.
Their descriptions seem to apply to each other, IME. Being mutable signs, they have some of each other's virtues and vices.
I've seen Pisces be critical, nagging, too focused on what you did wrong.
I've seen Virgo make excuses for their loved ones who clearly messed, up big time.
I've seen Pisces put their foot down and establish (healthy) boundaries.
I've seen Virgo get taken advantage of because they were too selfless and giving.
The opposite is also true.
I've seen Pisces meticulously plan something out, take care of the practical details, be designated driver, etc.
I've seen Virgo miss something completely obvious, or be too idealistic about something and have it fall through the cracks.
It's like they have this range of Virgo-Pisces behaviours that they tap into depending on how they're functioning that day.
So, what is the difference between them?
I guess Virgos are easier to cheer up.