Bernie Sanders and Elizabeth Warren are natural rivals for the leadership of the progressive wing of the Democratic Party, so you might be tempted to think they’re interchangeable. They’re not; they’re actually quite different, as follows:
Sanders is an ideologue. Like Jeremy Corbyn, his mind is largely stuck in the 1960s and 1970s, as evidenced by his odd fondness for attacking Henry Kissinger. His program is not really socialist, but his mentality is based on warmed-over Marxism. He has one speech, about Wall Street bankers and the “revolution.” His ideas about expanding the welfare state have lots of holes. He doesn’t really get identity politics. As a nominee, he would be a disaster.
Warren, as befits a professor, is a wonk. She isn’t a natural politician; when she turns on the intensity, she usually looks like she’s trying too hard. She has made a point of positioning herself as a capitalist reformer, not a socialist wannabe. She has been far more successful in merging class and identity concepts than Sanders. Her reform ideas have some merit, and she doesn’t insist on spending huge amounts of public money. Finally, she has lots of speeches, not just one.
Both of them would make better presidents than Trump, of course. Neither would be even close to my first choice for the Democrats’ nominee. Of the two, however, Warren is clearly the better option.