An architect designs the blueprint of abuilding before it is constructed. Similarly a systems analyst design the logic of a computer program.
An architect will design the blueprint using architectural drawing tools and techniques. Similarly a systems analyst will design a computer program using programming tools and techniques called algorithms and flowcharts.
A building contractor will construct the building according to the design and specifications in the blueprint laid down by the architect. Similarly, a computer programmer will male a computer program according to the algorithms and flowcharts made by the systems analyst.