What is the difference between Integrated Security = True and Integrated Security = SSPI?

Question

I have two apps that use Integrated Security. One assigns Integrated Security = true in the connection string, and the other sets Integrated Security = S

Answer 1

In my point of view,

If you dont use Integrated security=SSPI,then you need to hardcode the username and password in the connection string which means "relatively insecure" why because, all the employees have the access even ex-employee could use the information maliciously.