Algorithms and programs are different things. An implementation of the algorithm is called a program. Big-O is used for comparing of algorithms. An algorithm ca

Algorithms and programs are different things. An implementation of the algorithm is called a program. Big-O is used for comparing of algorithms. An algorithm can be implemented in different ways. Performance of the program can be measured precisely. Different implementations of the same algorithm will have different performance. When precise information is available, assumptions are useless. When precise information is not available, at design stage, assumptions are used to compare different algorithms.