I've met different descriptions before on photocells and photovoltaic cells... so there IS a difference (maybe in the way it's built, photocells might be simpler). More studious people must be summoned to this thread...
well, solar cells are photovoltaic cells, just a more specified name for a specified purpose...namely easier to say
I just kinda assumed that photocells were photovolatic cells.
but I just found a site, that sorta gives the difference. apparently a photocell is a variable resistor, so when light falls on it, its resistance is reduced.
read for yourselves.