It's easy to find the complete tournament rules for both arts.
Given that most techniques are allowed in either art, the real key is identifying which different rules have a significant impact on strategy.
The answer there is that Judo contests have rules which roughly include:
1. No "defensive" Judo while standing (bent over, grip without attacking, straightarm with grip);
2. No ground work without a throw attempt (can't sit to guard);
3. Limited time on the ground (without regular "progress", fighters get stood up by ref);
4. A clean throw ("ippon") ends the match.
BJJ doesn't include these rules, and as a net effect the resulting strategy and skill set of BJJ fighters is more applicable to other fighting contests (e.g.: submission grappling, no-gi, MMA).