Just get p/n TT2028170, which is the high flow thermostat. Call up a local store and make sure it's in stock, saves stuffing around ordering online.
The blistered / box annotation is just the packaging that the thermostat comes in (ie plastic "blister" pack or cardboard box).
That is actually very confusing what they have done there, listing a different prices / descriptions under the same p/n's.