I believe you are correct about Group B never having Blind Spot Monitoring. Here's a comparison:
View attachment 101224
The groups are actually far different from just the loss of Blind Spot Monitoring:
Laramie Level 1 Equipment Package (P1) (A66) — Includes Auto High-Beam Headlamp Control, rain-sensing windshield wipers, Blind Spot
Monitoring6 with Rear Cross-Path and Trailer Detection,7 foam bottle inserts (front doors only), tailgate-ajar switch, power-release
tailgate, 60/40 stadium-folding rear bench with manual recline and center 20-percent fold-down console (not available with Quad Cab®),
and ParkSense Front and Rear Park Assist with Rear ParkSense Stop.
Laramie Level 2 Equipment Package (P2) (A67) — Includes P1 Equipment Package, Uconnect 4C NAV, wireless charging pad (available with bucket
seats only), premium plus sound system, heated rear seat (three adjustment levels each) and rear underseat storage (Crew Cab models only)
Laramie Level A Equipment Group (A76) - Includes: Auto high beam headlamp control; Foam bottle insert (door trim panel); Parksense front/rear park assist with stop; Rain sensitive windshield wipers; Remote tailgate release; Rear 60/40 folding slip recline seat; Tailgate ajar warning lamp
Laramie Level B Equipment Group (A77) - Includes: Auto high beam headlamp control; Foam bottle insert (door trim panel); Parksense front/rear park assist with stop; Rain sensitive windshield wipers; Remote tailgate release; Rear 60/40 folding slip recline seat; Tailgate ajar warning lamp; 19 speakers Harman Kardon Premium sound; 4G LTE Wi-Fi Hot Spot; Disassociated Touchscreen Display; GPS Navigation; HD Radio; Heated Second Row Seats; Rear Underseat Compartment Storage; SiriusXM Guardian, 1-Year Trial; SiriusXM Traffic Plus, 5-Year SiriusXM Traffic Service; SiriusXM Travel Link, 5-Year Siriusxm Travel Link Service; Uconnect 4C Nav With 8.4" Display