Not. The main difference is in the pre-painting work 1) The medium. Old masters must made their own paint and then paint the portrait. And this is double of th

Not. The main difference is in the pre-painting work 1) The medium. Old masters must made their own paint and then paint the portrait. And this is double of the effort that modern masters need to do. This is not necessary anymore. you just buy it exactly made, in the exact amounts and the exact color tone, all the times. This means to grind the pigments to a fine dust (and many are poisonous), filter it, discard the extra materials until you have a pure paint. Mix it with eggs, or linem oil, or water and gum. Paint it and then let it dry for many months avoiding cracks in the painting. Paint products today have stuff to dry faster and more uniform. Using those you can accelerate the dry process or made it much more long, as you need. 2) Modern masters also copy, a lot, from photographs. All is done yet in a photograph. All the points and precise measures are here at the exact distance. This is much easier than building the structure slowly in your mind and improving it by iteration. 3) The eyes. With internet your work is seen by everybody in real time. If is good is good. You can use a lot of tricks to build a myth or spread your work. It was not so easy in the old ages.