Using Korg as an example, here is there TOTL Arranger http://www.korg.com/uk/products/synthesizers/pa4x/ and here is there TOTL Workstation http://www.korg.com/uk/products/synthesizers/kronos2/ if you compare them you will find significant differences.
I hope the above and the post by Spalding helps you to understand the differences better, however feel free to ask any questions if you are still confused about something.
Bill