If I "swipe down to reject", will caller get a chance to leave voicemail?
Google's Phone app Help implies that I can safely reject the calls:


  To reject the call, swipe the white circle to the bottom of the screen when your phone is locked, or tap Dismiss.


followed by:


  If you’ve set up a voice mailbox, rejected callers can leave a message.


That combined with some other research leads me to conclude that…


"rejecting"
"dismissing"
"declining"


…a call are all just different words for the same thing. And any of them will both make my phone stop ringing and send the caller to voicemail assuming it is available.

Whereas if my phone had a way to "silence" the call, it will make my own phone stop notifying me (ringing/vibrating) but the other caller will have to wait until it continues to ring for a while before it goes to voicemail.