There are many sword plants and quite a few hybrids and cultivated forms and colors. This is sort of a catch all category for other sword plants. The 2 others I have happen to be red.
The sword pictured to the left is a lovely plant with lots of dark green and red in the leaves. Mine have stayed small. I thought these were red melon swords when I bought them but they have been reproducing through side side plants and have never gotten any bigger. Perhaps they are a cultivated form of sword plant. They are a very nice plant.