Trail weight is the manufacturer's minimum weight for a barebones setup. Trail weight excludes "extra" items like stuff sacks, pole repair kits, patch kits, etc.
Here's a simple chart showing the difference between trail weight and packed weight:
Guy lines and repair kits aren't usually included by most manufacturers.
Some manufacturers choose to include them; others say they're optional
Trail Weight Isn't A Standard Measurement
Every manufacturer can decide for themselves what
This means they can make the trail weight much lower than what you'll actually experience when you're using the gear.
You should always go with the packed weight when you're planning how much your gear will weigh.