For me:
Helix Floor has scribble strips, as mentioned already. They make it a lot easier to see in the dark, if you have an involved show. They are also a separate source of light on a dark stage as a bonus. Like I played one show where the stage light was completely out for about 10 seconds. I was able to navigate the stage thanks to having the Helix as my beacon of light :) Also, the Floor has a 10-stomp mode, that the LT does not have, plus more effects loops.
Helix LT has a flimsier expression pedal. If you don't click the pedal in to switch between EXP 1/2, then the onboard pedal will last you just fine for years and years. LT has no scribble strips, but the performance view where the snapshot names are displayed on the screen is superior to the Helix Floor if you are playing outdoors. Scribble strips are more difficult to see if you are playing outdoors, compared to the "virtual" scribble strips that LT offers.
If you don't plan on switching your sounds too much throughout your show, and you don't do all these dramatic dark stage moments where you emerge out of the fog and all that theatrics -- just get the LT. If you are worried about the expression pedal not being too robust, you can always get an external pedal and use that. Save yourself like 700 USD.