A write (or print) is basically a press + release.
So to send "normal" text, writing or printing is fine. eg.
Keyboard.print ("hi there");
However if you want to press a key (eg. Shift) and then press another key (eg. Enter) then you would probably do 2 x press and then a releaseAll.
This is the code for write:
size_t Keyboard_::write(uint8_t c)
uint8_t p = press(c); // Keydown
uint8_t r = release(c); // Keyup
return (p); // just return the result of press() since release() almost always returns 1
So you can see it just presses and releases the required key.