Those two questions can be heard again and again from both new and experienced genealogists...I have been known to ask them myself.
In a recent edition of his Online Newsletter, Dick Eastman has written an excellent and detailed answer to those two questions. He even goes on to address what he sees as the future of genealogy programs and record keeping.
It will take some time to read the article because Dick as give the subject extensive treatment, but it is worth the effort. So go get a cup of your favorite beverage, and then set back and read the article at http://tinyurl.com/27s3d97.