AdWords Synonyms:

With this feature, SECockpit queries the Google AdWords Keyword Tool (more commonly known as the Google Keyword Planner), to get alternative suggestions, based on a seed keyword or URL. These keywords are sometimes only loosely related to the seed keyword but they are usually fairly popular, in terms of search volume.

Google Suggest: 

With this feature, SECockpit scrapes as many Google suggestions (what you see when you start typing a search term in the Google search bar) as possible. These keywords are usually very closely related to the original seed keyword. They are often long-tail keywords, sometimes with very low or no search volume. The volume of keywords found is often high and there are usually some very valuable keywords among the mix (keywords you wouldn't find using the GKT source).

Related searches: 

With this feature, SECockpit scrapes the "related search terms" added to the bottom of a Google search results page. These keywords are also usually long-tail keywords and are again a different set of keywords than are shown in either the keyword tool or the suggestions.