Google Adwords search volume tool is highly effective and extremely easy to use. If you’re new to keyword research and just want some quick info on the search volume and competition level of a few keywords you have in mind, this is a great tool to use. Just enter in the specific keywords that you want to compare, and then view the results. You’ll be able to see the search volume, general competition level, and suggested Adwords bid.
Long Tail Pro is a keyword research tool that helps you quickly find low competition keywords for your website. In particular, the tool is built for people doing SEO (search engine optimization) as opposed to people doing paid ads (Google Adwords PPC). I'm sure there are some advertisers that use the tool for paid ad keyword research, but the tool was built for SEO keyword research.