I just took a quick look at the L200 vs the SJ200. The L200 is actually a V/Hz control type as opposed to the SJ200's open loop vector (sensorless vector.) Both can be run in constant or variable torque modes. With some mfgs a variable torque setting may allow a higher horsepower output because it reduces the overload current allowed. Centrifugal fans and pumps are ideal examples of variable torque loads, requiring very little if any overcurrent at low frequencies.
www.driveswarehouse.com is mislabeling the drives with the constant and variable torque labels, although it is true that many (most) variable torque loads work fine (if not better sometimes) with V/Hz control.
On the flip side of all this, the SJ200 will have much better torque than the L200, especially at very low speeds. It will also have tighter speed control. I didn't look for it, but the L200 can possibly have slip comp added so you can manually add in compensation to correct for speed droop when the load increases. You can also add torque boost. The reality for most machine tools is that this is probably not a big issue. Situations requiring vector drives and greater than 100% torque capability tend not to be machine tools. You don't usually start a lathe or mill spindle with the tool already buried in the work.
So depending on your application, it's up to you to decide if the extra $$$ are worth it.