Is product opportunity frontier the same as PPF? In CFA level 1 reading 14, they have this term called Production Opportunity frontier and it is defined as 

Curve describing the maximum number of units of one good a company can produce, for any given number of the other good that it chooses to manufacture.

The graph is a straight line



Is it the same thing as what is commonly known Production Possibility Frontier with the curved line?
Yes. The "curved line" clearly fits your definition as well. The PPF is curved if (but not only if) there are diminishing returns to inputs such as labor and capital. See also
https://en.wikipedia.org/wiki/Production%E2%80%93possibility_frontier