What is the difference between the Delta LT and the Cardigan Caliber? They seem to use the same material.
The Delta LT and Cardigan Caliber are indeed made of the same Polartec Classic 100 Micro Velour fleece material. The differences between the two are subtle and mostly aesthetic. The main difference is the Delta LT is a bit lighter and has a slimmer fit.
Delta is made of a waffle fleece and is a touch thinner by feel than the micro velour fleece on the Caliber. For spring '13 the caliber gets a makeover and new fleece fabric.
Chris is correct that the Delta fits slimmer.