I wouldn't worry too much unless the dog is showing other signs of illness.

My two border collies are the same size and about the same weight, jess might be slightly heavier than Mist but not much. Mist is smoother coated, not totally smooth like a lab though and it's still very dense and thick and Jess is rougher coated but Mist never drank as much as what Jess seemed to drink.
They were both fed the same diet. Dry food but it was soaked, they didn't generally eat it dry. They basically live together and have the same lifestyle, amount of exercise, everything.

I'd notice when I walked them and they came to a puddle that Jess often drank a lot longer than Mist and sometimes Mist wouldn't bother at all. The other dogs of my dads tended to drink more than Mist too and Mist panted less than the others as well even though the cold didn't affect her anymore than the others. Being a border collie from the Scottish highlands and being born and bred outdoors where working sheepdogs are generally kept, she was a tough and hardy dog.

Now that she is older, she does drink a bit more but not excessive amounts. I think it's because she wears out easier and so pants more and this can cause thirst because a lot of moisture is lost through the tongue.

I think it is just a natural variation. As a human, I don't drink that much really. Nowhere near the amount they say you should. I have tried but it makes me feel really full, bloated and I have to go pee every 10 minutes which isn't practical in everyday life. I can drink very little and my urine is still very pale yellow so I'm sure these variations exist in dogs too.

If she shows other signs of being ill, then have her checked but I really don't think you need to worry otherwise.