I Googled it and this is what I found: There are two types of osteoporosis: Type I osteoporosis (postmenopausal osteoporosis) generally develops in women after menopause when the amount of estrogen in the body greatly decreases. ... Type II osteoporosis (senile osteoporosis) typically happens after the age of 70 and affects women twice as frequently as men.

This is what I found at the Spine Health site online.

There are two types of osteoporosis:
Type I osteoporosis (postmenopausal osteoporosis) generally develops in women after menopause when the amount of estrogen in the body greatly decreases. ...
Type II osteoporosis (senile osteoporosis) typically happens after the age of 70 and affects women twice as frequently as men.

What is Osteoporosis? - Spine-Health
Spine-Health › conditions › what-osteop...

Isn’t osteoarthritis to do with joints (and osteoporosis is brittle bones)?

Generally what is posted above is correct. Do you research much on your computer? I would start there with a general search. I believe you will achieve results you are looking for.

I am wonder the same thing, Janine. What is the difference between 1 and 2?