What is the key difference between a bulkhead and a baffle in a liquid cargo tank, as described in the AAMVA Manual?

49 CFR 383.119(c); AAMVA CDL Manual Section 8.2.3-8.2.4, "Bulkheads" and "Baffled Tanks," p.8-8-2

This is one of the most commonly tested distinctions in the tanker endorsement, since the manual's own review section opens with this exact question. Confusing the two terms is an easy way to lose points, so keeping "bulkhead = separate compartments" and "baffle = holes that slow surge in one compartment" straight is essential.