Take one topic — the reactivity of carbonyl compounds toward nucleophilic addition — and watch how differently NEET and JEE actually test it.
How NEET tests it
NEET wants speed and a single correct option. A typical question just asks you to rank reactivity:
You need the order memorized cold — aldehydes exceed ketones because of reduced steric hindrance and smaller donation to the carbonyl carbon — but NEET rarely asks you to justify it in the answer. One correct ranking, 45 seconds, move on.
How JEE Main tests it
JEE Main usually keeps the same fact but wraps it in a short numerical or "which of the following is most reactive toward HCN addition" question with 4-5 real structures instead of general formulas — so you can't just recall the rule, you have to correctly classify each structure as aldehyde/ketone/aromatic first, then apply the rule.
How JEE Advanced tests it
JEE Advanced tends to combine this with a second concept in the same question — for example, pairing carbonyl reactivity with the aldol vs Cannizzaro decision:
A student who only memorized the reactivity order (without understanding why aromatic aldehydes are both less reactive toward addition and prone to Cannizzaro instead of aldol) will get an Advanced-level multi-statement question wrong even with the "easy" fact memorized correctly.
What this means for your prep
If you're preparing for boards and NEET together, memorizing the ranking is enough for one exam but not the other. The safer approach: learn the reason behind the order once — steric hindrance and inductive donation — and the same understanding answers NEET's recall question, JEE Main's structure-matching question, and JEE Advanced's multi-concept question, instead of needing three separate revision passes.