The diagram represents the evolution of cutting tools used by ancient people in the Stone Age showing these tools from different perspective and giving information about their size.
If to look at a front view, tool A that was used 1.4 million years ago has a sharpened and oblong form and it is about 10 centimeters long, while tool B that was used 0.8 million years ago is oval and its tip is more pointed and it is nearly the same size as tool A.
If to compare side view of both tools, it can be clearly seen that tool A is less sharp than tool B and it is way thicker. Moreover, tool A is not so symmetrical as tool B, so tool B seems more improved.
In general, it is obvious that over 0.6 million years period people were able to improve their skills in making cutting tools as tool B that was made 0.8 million years ago looks more useful and upgraded.