What’s the difference?
The former is what contractors do to land jobs.
The latter is what Buyers and Sellers negotiating a deal need to do to resolve inspection issues (step #2: decide who’s responsible, the Buyer or Seller — unless the lender takes the decision out of their hands).
While estimating repairs can lead to actual work, the washout rate is high enough that contractors don’t exactly race to return calls from unfamiliar Realtors (at least, that’s been my experience).
Or if contractors do visit the home, they spend about 5 minutes and scratch a (non-binding) number on the back of an envelope.
One solution to the above?
Contractors who charge for their time to do a professional estimate, but credit that amount against the job if they’re later hired.