I'm pretty sure GP means actual quarantine. We are not quarantining hundreds of millions. We are advising hundreds of millions to practice social distancing.
Depends on the circumstances. I live alone and work from home, so there's very little difference for me between the current situation and an indefinite quarantine.
For anyone who exercises daily, there's a really big difference!
On a continuum from my usual daily activities (gym for lifting, climbing, ultimate, soccer) and my current activities (bodyweight exercises in my home and runs around my neighbourhood), I’m much closer to indefinite quarantine than I am to a normal state of affairs.