Halfnut pretty much covered the basics. Either the 10K or 10L is a good lathe. The 10L is heavier all around.
The 10K takes 6K collets 5/8" maximum capacity, and has a standard quick-change gearbox. The 10L takes 5C collets 1 1/8" (?) maximum capacity and has an expanded range gearbox (at least later models do) that can cut 27 tpi and 30 tpi and such. The 10K needs an extra change gear for those threads; in practice, it is usually of little significance.
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