peachrules-san,
Some people were having difficulty using the 'new format' PDFs with their devices or computer so a "Lite" version is available for download for those that would like lesson PDFs in the style/format they were in before the change. There is a number of benefits to the new PDFs, for example the PDFs are now searchable and having bookmarking.
Go ahead and try the new PDFs, if they don't work for you in your study environment for whatever reason then the Lite version is of course available.
