Basic difference, since they don't list it? Probably the flow restriction piece.
If you need 50 to 100 gallons of RO water a day, or week even, you need a unit that uses standard -full size- cartridges. The small ones on the links you provided will quickly end up costing more than a complete off the shelf home unit.
With an off the shelf RO system cartridges for standard size units can be purchased anywhere filter components are sold as the manufactures all use the same size filter modules.
For anyone looking at RO, I suggest watching several of the videos at http://www.bulkreefsupply.com/video/...y/Instructions
After that you will know a lot more than the filter sales people - most anywhere.