You can use this tool while searching for ad group ideas or keywords. Keyword planner acts like a workshop that you can use to expand existing network search network campaigns or build new ones. The tool can allow you to search for AdWords tool ideas or keywords, view the performance of a list of keywords, retrieve historic statistics, and develop a new list of keywords by multiplying many keywords lists together. A free keyword planner, AdWords tool can also assist the user in selecting a list of competitive budgets and bids that you can include in your campaigns. You can utilize keyword planner in laying the foundation of a successful online campaign whether you are a highly experienced pro or new to online. All you need is a Google AdWords account and you will be ready to sign in and get on the move.
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.