The difference between the straight line PPC and a concave PPC is the difference in opportunity cost.
The production possibilities curve refers to a graph or economic model that shows the maximum combinations of goods and services, any two categories of goods that can be produced from a fixed amount of resources.
When the production possibilities curve is a straight line, the opportunity costs are the same no matter how far you move along the curve. When the production possibilities curve is concave (bowed out), the opportunity costs increase as you move along the curve but when the production possibilities curve is convex (bowed in), the opportunity costs are decreasing.
Read more about production possibility curve
brainly.com/question/2601596
#SPJ1