Bob,
Like most companies, every so often Mentor will release new part numbers to offer solutions that better fit our customer's needs, or for competitive reasons. We have just introduced PADS Standard, Standard Plus, and Professional. These offer various levels of features and functionality at different price points. This allows our customers to choose which one best fits their needs based on their requirements and budget. BTW - starting price is only $5,000 (including 1st year support)!
Go to pads.com, where there is a ton of information on these new solutions, including a configuration matrix so you can see what's included in each, or, as Vern suggests, contact your sales person for more information.
Jim