SEO and SEM go hand in hand but are very much different from each other. Search Engine Optimization is a technique by which you improve your search rank and drive traffic to your website. Search Engine Marketing is rather a broader term that encompasses SEO as well. It includes paid or sponsored advertisement, ensuring more visibility of your website.
I was an early user of products like Market Samurai and the Google keyword tool back when they both actually told you something useful. This isn't exactly like the early days of SEO, but it's close. You can search keywords and actually return quality, actionable data that you can use in your AdWords campaigns, on-site SEO, and Social Media optimization.
Are you a business owner, online marketer or content creator? If so, most likely you would like more people to visit your website, read your content and buy your products or services. The easiest way to achieve it is to find out what your potential customers or readers are searching for on Google and create content on your website around these topics.
SEMrush’s Marketing Calendar is a work in progress. It isn’t the most powerful tool which will make it worth a purchase yet. Though if you’re already part of the SEMrush ecosystem, this is free for you to use. But it is only useful if you’re managing multiple campaigns. Plus it falls short in the sense that it does not prompt you about approaching deadlines, and events which would be a useful feature in a future update.
In general, I love Semrush. It's a lot of information. Even if some of the information in the database is a little outdated, the huge amount of data and ideas you can get from Semrush is worth it. You even get extra things like social networking tools. It is ideal for SEO and PPC campaigns. I can see the data on my website with a single click of a button. It also allows me to keep track of my keywords, but I think they are not as accurate or that the data has not been updated recently. SEMrush is a great tool for any online business. It helped us to rank higher in the search engines. In general, I must say that I would recommend the tool to other people. The speed of the scans is a great advantage, you can set up a scan in progress and in a matter of minutes it is complete.
Ahrefs boasts the best link database among any system out there. It does most everything -- link monitoring, alerts, calculated metrics, the richest clickstream blend out there, and much more. Its UI is cluttered in a good way and the company has quick and polite support. And Tim Soulo -- the public face of Ahrefs -- has done a ton of good for the SEO community.
SEMrush is one of the most comprehensive SEO and SEM tools out there. However, it is not a tool for the budding entrepreneur who is still getting to grips with laying out their website or has no idea what a landing page is. It is a powerful tool that requires a degree of experience. Some tools are obviously more complex than others. Then there are tools that some businesses may never use. Though in the grand scheme of things the goal of every feature ranging from its backlinks monitoring to keyword research, competitor analysis is to give you a leg up on the competition.
Pros: SEMRush provides loads of actionable data from SEO to PPC to Social. I use it a lot for Internet Advertising / PPC research on what competitors are doing - what are their ads saying, what keywords do they target, what is their estimated ad spend, etc all in one place. It helps with not only search ads - but also display ads - this super feature helps us understand what the competition is up to. It helps in keyword research for organic SEO as well as paid traffic. In terms of SEO it helps track position on organic search results (SERPS), SEO audit including technical stuff and backlinks.
The thing that I liked the best about Ahrefs is that it contains a huge database of backlinks when I've checked my own website and my competitor's websites. This has allowed me to dig deeper and find out their exact linkbuilding and SEO strategies. Ahref contains a lot of tools and features that will make the life of an SEO professional or webmaster who wants more search engine traffic a lot easier. One of these features is the batch analysis feature. Basically, instead of entering your competitor's backlinks one at a time you could actually enter it once. This allows you to quickly check on the SEO metrics for a lot of competitor URLs in just one click.
The Backlink Analytics tool can provide lengthy lists of competitor's backlinks that can be exported in spreadsheet formats. You can see your competitors backlink strategies including legitimate (blogs, directories) and illegitimate methods for gaining domain and site authority on Google. I also appreciate the keyword rankings, as it allows for easy reporting and tracking of SEO optimization strategies and keyword campaigns. Great tools for tracking keywords campaigns against similar business as well.