I chose to compare Info Trac Junior to Info Trac Student. Both are good databases that I recommend to my students. Using some of the same health topics that our students look up for health I compared the two databases. On my of the topics like teen smoking, Info Trac Student returned more hits, included higher reading levels and a larger selection of sources. I would assume this is because the Junior is geared more and filtered more for middle school audiences. Both have the ability to read the article for students which is useful and both have a good citation tool available which is helpful. The sources are published resources some more well known then others and some that are in the Student version might require students to check out the appropriateness of the source. Just because it is published doesn't always mean its right or credible, it just means we know who the author is and who is taking responsibility for the information.

Academic OneFile - 40,632,752, General OneFile - 99,812,347 Educators 7,885,112. All three of the databases have a variety of resources written at a higher reading level. All three include common resources along with professional journals and magazines written for specific fields. General One File has over twice as many articles as Academic and Educators Resource has even less than Academic. All three let you search for full text, images and peer reviewed articles, something that is useful for higher level research. All three are updated daily. There are many areas that overlap but not all and I would recommend searching all three for topics.
All the databases I looked at were easy to search, very similar to the search engines that students use. They also have advanced search options and search history, the ability to mark and retrieve articles. They also have features to send the articles as email, print, download, and save as mp3. You can also have the articles translated.
Citation - 1
I recommend using the citation tools, when ever available (not all databases have the citation too.) I use MLA 7 which means the URL is optional. With my students I tell them that since I need to log into the database to get back to the article, the URL is optional.
Ault, Alicia. "Smoking Rates in Teens Show a Leveling Off." Pediatric News 44.10 (2010): 31. General OneFile. Web. 5 Dec. 2010.
Citation - 2
Spasov, Peter B., Jason Apple, Champ Davis, Christoper Page, and Melissa Harcom. "Dealmakers' Almanac; Market Observers Break Out Their Crystal Balls to Forecast What the New Year Will Bring." Mergers & Acquisitions: The Dealmaker's Journal1 Dec. 2010: 42. General One File. Web. 5 Dec. 2010.
No matter which tools you use I tell students they still need to edit for capitals and remember that garbage in means garbage out. You still need to know which information to enter where and what needs to be entered. The tools are definitely helpful and make citations for teachers and students easier.