Answer:
Structured programming also known as Modular programming in which the program is made as a single structure.The execution is instruction by instruction.It mainly focuses on improving the quality,clarity and development time of a computer program.
The top-down approach works by breaking a complex algorithm into smaller parts called modules. The modules keep breaking until there is no space left for breaking them without hindering the originality.The breaking of the modules is prohibited after achieving a certain level of modularity . C language uses this approach.
Bottom up works exactly opposite of how the top-down approach works.This approach works in the most elemental level of solving a problem and going up with combination of several parts of the solution to achieve required results.