Is there any difference between Linking Materials and selecting the same material for 3 objects individually?
I'm not familiar with this particular course, but I'm assuming you're talking about the linking data hotkey Ctrl+L->material. Yes this shares the same material on all selected objects or as you put it manually assigning the same material to each object/material slots. Note: you can assign the same material to different material slots also.
And if you have the same material on 3 different objects, if you change parameter on the material it will reflect the same change in all 3 objects, since all 3 are sharing the same material.
So no, there is no difference, if you put a material on 3 different objects or if you just link them, you're basically doing the same thing.
It's more or less the same Maciek mmaciekkreft ,
but Linking Materials is usually faster...and you are linking all Material Slots at the same time...
The Cube has 6 Materials and the Monkey has Material slots 1, 2 and 3 assigned and the Torus slots 4, 5 and 6:
Link Materials does this:
(Not a very practical example, I know.)