Here's how I like to construe the differences in these words. [Yes, I do believe they are not synonymous.]
Guess: Pulled out of thin air. "Oh yeah, sure, no problem, easy-peazy! I can get all my darts into the target! Um --- uh --- er --- which target was that?"
Estimate: Prediction of the future, based upon past results, or research. "In my previous rounds I've hit the target. I'm improving. I think I have a 65% chance."
Accurate: The real data, the actual results --- in a broad sense. "I did hit the target."
Precise: Specific detail, categorization, analysis. "I hit the bulls-eye once, the triple 20 once, and one dart hit the target, but outside the scoring rings."
When you are writing and periodically reviewing your business plan think seriously about these concepts.
Guess: Leave these blue-sky, gross generalizations out. Venture Capitalists and investors can tell when you pulled these out of ....... thin air.
Estimate: Do your research. Forecasting is more than guessing. It is grounded in past experience and analysis. Cite your sources.
Accurate: Keep your records and use all your results. You can use the big picture, but it may not serve you well if your view is too broad. "The fewer the data points, the smoother the curve."
Precise: Be honest here. Look closely. Continue to do your periodic scheduled reviews. Do your analysis thoroughly and completely, even if the conclusions may not be exactly what you wanted to find. If you throw out half of your data in order to reach correspondence with your estimates, you are neither accurate, precise, nor honest with yourself nor with everyone else participating in your business.
Palo Alto Software