Your question seems to be both about content and interpersonal relationships / dynamics. I think it's very helpful to split out the differences between the groups along those lines.
In terms of substantive content and focus, I think the three other responders outline very well; particularly on attitudes towards AGI timelines and types of models they are concerned about.
In terms of the interpersonal dynamics, my personal take is we're seeing a clash between left / social-justice and EA / long-termism play out stronger in this content area than most others, though to date I haven't seen any animus from the EA / long-termist side. In terms of explaining the clash, I guess it depends how detailed you want to get.
Could be minimalistic and sum it up as one or both sides hold stereotypical threat models of the other, and are not investigating these models but rather attacking based on them.
Could expand and explain why EA / long-termism evokes such a strong threat response to people from the left, especially marginalised communities and individuals who have been punished for putting forward ethical views - like Gebru herself.
I think the latter is important but requires lots of careful reflection and openness to their world views, which I think requires a much longer piece. (And if anyone is interested in collaborating on this, would be delighted!)