The primary difference is that Long Tail Pro is a big time saver over MS. With Long Tail Pro you are able to enter in multiple seed keywords at once (rather than just 1 with MS). So, instead of entering in 1 seed keyword, waiting five minutes, then going back and entering in one more; you can enter 5 seed keywords (for example), hit generate and then see all the keyword ideas at once!
Keyword Researcher is designed to search the Autocomplete databases of Google, YouTube, and even That's a lot of keyword sources! As you probably know, if you're building an authority site, or if you would like to become a dominant player in your niche, then starting with a large database of keywords (that your customers are actually typing in) is a powerful marketing tool.

The reason I sometimes use this facility with the GKP is to find volume amounts for the keywords I’ve chosen. But, these days, it’s not so important. As long as the Long Tail Keyword makes sense and is something I would put into a search engine, then it’s good enough. Sometimes the most blazingly obvious keywords are often over looked by eager, trying-to-be-clever marketers. Sometimes you need a tool to highlight them.
1) Ahrefs to quickly see “the big picture” when it comes to any keyword I'm researching. I can instantly see the top holders in the SERPs. I then immediately take the top holders list and go check out their sites. I need to make sure I can beat them content-wise, otherwise I will search for another keyword to try and rank for, or perhaps go down the long-tail route. The Ahrefs tool and data quality get better and better every year. It's one of my favorite tools.
hello Frank I just started affiliate from Amazon and I am interested long tail pro and find some store where can make sure me for help support in case problem with program I already review around your site and that make me following your site.I have plan to by long tail pro with this site could you please inform me for cost it,your promotion and payment I also have paypal account.thanks

You don’t really need to worry about the volume size either. Too big a number just means you will have to work harder to get ranked in Google. It’s now quite commonplace to see SEO people say it’s best to just go with your gut feeling on a keyword. Just go for something you would type into Google search yourself instead of beating yourself up trying to find that ‘one’ killer keyword.

"I've been doing keyword research for years, and I can tell you that dealing with hundreds of keywords and dozens of spreadsheets is enough to make anyone lose the will to live. Keyword Researcher is great because not only does it let you easily find keywords that people are actually searching for, but it has a clean and simple interface that makes it easy to keep track of what you've found. If I'm stuck and need some new ideas, I just fire it up and usually find several things to write about in a few minutes."
Keywords are supplied with accurate, clickstream-based metrics, some of which are exclusive to Ahrefs. For example, Clicks and Clicks Per Search can give you a better idea of how much traffic your content can get. That’s a burning issue today – many queries never translate into clicks because Google reveals answers for them at the top of SERP (i.e., Knowledge Card).

You can use Keyword Researcher Pro with the best free keyword research tool out there, Google KW planner. Importing and exporting data is as easy as clicking a button. It’s all done at lightening speed too. There are tutorials of how to do this in video form on the sales page here and they show just how easy this tool is for finding those long tail keywords.
The limit on manual keywords could be higher.  I personally wish we could input 10,000 keywords at a time, instead of 200.  However, I understand the costs that Long Tail Pro has to maintain each time a new manual keyword is input.  Not a deal breaker, I just wish the limit was higher. (To be fair, I don't think most keyword tools have a bulk manual option at all).