It's like the difference between building a Bird house, Dog house, people house, mansion, large building and a sky scraper... it's different levels of planning,

It's like the difference between building a Bird house, Dog house, people house, mansion, large building and a sky scraper... it's different levels of planning, preparation and logistics involved. A lot of software can (or at least should) be done at the bird or dog house level... pretty easy to replace.