These include heart disease, osteoporosis, dementia, Parkinsonism, cognitive
and memory impairment, mood disorders (mood swings, depression), anxiety, poor sleep quality, visual changes, skin changes, muscle wasting, hot flushes, vaginal atrophy. Estrogen "replacement" mitigates some of these risks as well as restoring some quality of life.
As far as your question about estradiol versus HRT, you may be referring to "bio-identical" versus synthetic.