And I've just noticed there's a thorough answer already given below by an expert. 🙄 I just copied mine as it was written on the internet.
Please accept my apologies. ☺️

OK, I've just looked into this myself as it appears nobody knows!

Type 1 is postmenopausal osteoporosis and happens between 15 and 20 years after going through the menopause and appears to be caused by estrogen deficiency.

Type 2 is age related and occurs in men and women over the age of 75. It's usually caused by a very long time calcium deficiency.
Although men can get it, it appears to affect women more.

So the answer is, it's as simple as being age related!
That makes me type 1.

Sorry I can't help you, but I have the same question as well if anyone can help please. Thank you.