If I can generalize, the social enterprise / impact investing space focuses more on scale, while the social justice / activism space focuses more on leverage.
This makes sense: social enterprises are rewarded when they grow in size, and the capital in impact investing pipes is intended to beget more capital. In the social justice / advocacy space, there is more focus on creating impact through systems, and therefore organizations must create leverage to influence that system. Rarely will one organization — through its sheer size — tip a system, but if it works through its leverage points, and in concert with other organizations working through leverage points, then a coordinated effort might be more successful.
Embracing the idea of leverage (instead of just scale) will likely mean smaller organizations, less opportunities for follow-on rounds of impact investments, and maybe less directly-attributable impact...all of which would challenge the vogue notions of scale, proof, and credit. But in exchange, you might begin to work further upstream on issues whose downstream consequences necessitate big social enterprises and lots of impact investing capital.