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!
Creating a psychologically alluring title is important--because search engines will rank our document (in part) based on how many clicks the title is getting--relative to other articles on Google's Search Results Page (SERP). Hence, a title that has some stylistic panache, will (in theory) ultimately rank higher than a title that doesn't have anything eye-catching about it.
Recently I had a dilemma with one of my projects, it is related to ecards and many people still using word “cards” instead of “ecards” but Google Keyword Planner and some other tools showed almost the same information for both keywords. At the same time I did not want to have many words “cards” and “ecards” on the landing pages. Semrush helped very much. I found correct data and made a nice PPC campaign.
1. AdWords Keyword Planner - It's still the standard, although Google keeps making changes that just aren't helpful. I get that they want us to treat closely-related keywords in such a way that we're not creating multiple pages when we should just have one, but I'd appreciate it if they'd still break down the volume for each keyword that makes up a group (or at least list the keywords they're clumping together into a group).
So whilst Long Tail Pro has just continued to grow in revenue every single year and comes highly recommended, you may want to check if all the important features are fully functioning before signing up. Especially the KC feature (keyword competitiveness) as it is so fundamental to keyword research and making an informed choice on whether or not to go into a particular niche.
This comes with a monthly fee though, so why have that recurring revenue drain when you can just get MS or LTP for that matter on a one off fee. They are both virtually the same in my opinion. This is the only thing that is stopping me from buying the software. If the calculation of keyword difficulty was included in the one off fee, i wouldn’t mind paying the full $97.
The WordStream suite of Keyword Tools is an integrated and actionable set of keyword tools designed to help search marketers with keyword search, keyword suggestion, keyword grouping, PPC keyword research, keyword analysis, long-tail keyword research, and negative keyword discovery, going beyond the capabilities that a typical free keyword tool can offer.
I want to share how and why I sold the company in order to both educate and inspire potential software entrepreneurs.  I certainly don't know everything and obviously companies sell for much more than I sold Long Tail Pro for (I won't be featured in Tech Crunch anytime soon); however, I'm willing to share what I have learned and hopefully that can be beneficial to a few of you.