The Best Actress winner for 2000 was Julia Roberts for Erin Brockovich. That performance was a beguiling mixture of diva and mensch so instead I'm going to focus on two other Best Acrtess nominees that year:
Diva: Ellen Burstyn, Requiem for a Dream
Mensch: Laura Linney, You Can Count On Me
Burstyn's performance is showy and impressive, Linney's is delicate understated. Even the clips I chose highlight the diva/mensch duality - - Bursytn is having her solo moment whereas Linney is being the best partner to her co-star, doing more reacting than acting.