Look at the engineered plan from each PB. This will show rebar spacing, gunite thickness, and mix design presented as minimum PSI for gunite. Ask for a copy of their engineer stamped structural plan.
Structural parameters are usually pretty similar. Other questions should be about deck preparation. Do they compact under deck? Do they water jet trenches? Do they use a sand or rock base under the deck?
What size plumbing is being used? What type of filter?(i.e. Sand, DE, Mod Media) Are they installing a variable speed pump? Are you getting a pool cleaner? An auto-fill?