What’s the difference between TSA a general check in?

Tsa is the security you must go through to get from the ticket counter check in and proceeding to the gate your airplane is located

You can check in by phone in some app, I used who we booked with. So our check in & tickets was done by then just scanning my phone. TSA is the security you go thru, they check your aerosols, soaps shampoo etc. are all recommended sizes. Also a lot of the buildings are non smoking and I had to go thru them at every airport to get to the gate. They XRay your suitcases, purses, bags etc.. and can make you open it. Take off your shoes stand in a human air vacuums & dogs sniffing. It’s for safety!

You have to check in before heading to tsa