Note that this thread follows two recent discussions, both started by kashifkb, and from what I can tell are essentially asking the same question... which is why you can't find third party tools don't match each other or match what you see when you look at Google serps. This post IMO is one more variant of that.
I won't try to answer that question in any great detail now, except to say that...
a) some tools return PPC results, and some return organic searches, and some both.
b) some tools use their own proprietary interpretations of a Google supplied API feed, and...
c) some tools scrape Google serps (which is against Google's TOS), organic and/or ads. The scraping tools are all different, with different methodologies, times, places, and sample sizes, and they inevitably are going going to return different numbers. They are at best a small sample that gets extrapolated up (and the errors get multiplied).
Here are the two recent threads, with a quoted response from each thread, which suggests that the ideal tool simply doesn't exist. Accurate Keyword Position Analyzer Aug-Sept 2017 https://www.webmasterworld.com/google/4865116.htm
There is no tool that can give you accurate picture, because there is no one keyword position (To be clear keyword position == position of you website in serp when a specific keyword is searched). Personalization, time of day, year, month, location, browsing history, and many more factors all influence what sites are returned for any given search. As such it is simply impossible for any tool to provide an accurate response. How to Track Keyword Positions Nov-Dec 2017 https://www.webmasterworld.com/google/4879020.htm
Unfortunately, there is no automated tool that is all of those things, despite what some may suggest. You can use some of the tools that are available, but they are only accurate as far as the tool is concerned, and do not give a true reflection of what a genuine searcher would see. The tools are helpful, but you should not rely upon them.
I'd like to get the poster's feedback about what it is that we haven't answered. It's also very unusual for us to have multiple threads open on the same topic, as it creates a very confusing situation for users... and it's very unusual that we have discussions in this forum comparing SEO tools. Normally, as our Charter explains, that's an area we try to avoid, as it leaves us open to promotion and spam.