What's the difference between a tri-fold garment bag and a rolling garment bag?

A tri-fold (like the TUMI Alpha) folds suits twice and packs flat, so it stows easily in overheads or under a seat but holds less. A rolling garment bag (like the Briggs & Riley Baseline upright) keeps clothes longer with fewer folds and has wheels for heavier loads, at the cost of more bulk, more weight, and a higher price.