What Real MC said. A good thing to note - you can tell the differences by looking at the bottom of the tine blocks as well. There were also different iterations of the taper itself.
Besides the black tine blocks which are easy to recognize as the earliest untapered tine, on the bottom of the tine blocks you can see the different sizes and shapes of the "circle." In your first picture, I can see at least 3 types of tines.
1) where the flat part of the circle goes almost to the edges of the blocks (black and silver blocks, no taper)
2) slightly smaller circle, and a rounding off of the edges of the tine block with a gentle taper
3) even smaller circle (tine block almost looks polished) and very rounded off tine block edges, sharper taper
Basically, the taper got sharper gradually over time.
