a full manual camera u have to adjust focus, aperture and
shutter urself.
semi-auto u can choose to change one or more of those settings, and
the cam will choose the best settings for the rest that u didn't
for you.
full auto u dun choose anything, the cam does it for u.
most semi-auto cams of course, have a full auto mode. the converse
is not necessarily true.
also, most semi-autos have have a full manual mode (technically),
since in a semi-auto, u can set it to manual more for exposure
settings (shutter and aperture) and change the lens to use MF
(manual focus) mode.
