The worth, or value of the property you want to buy, will determine how much a lender is willing to give you to buy that particular piece of real estate.
A home appraisal is not the same thing as an inspection.
If you're buying a home, you'll want to hire an experienced home inspector to point out any potential problems that could turn into costly nightmares in the future. Property appraisers will likely make note of any obvious issues, but they won't test your heat and air, check the chimney or determine if your plumbing is up to code. That's the job of the inspector.
A home inspection is part of the process of selling a house, knowing the exact amount of money the house is worth determines if it's overpriced or priced below the average market value.