In the US nonprofit sector it's possible to have two nonprofits focused on the same subject but using different strategies to actually accomplish different results. Each nonprofit's board uses a Theory of Change is what informs these differences. The Theory of Change is a purposeful exercise for reaching or clarifying mission. The Theory of Change also serves to guide staff, volunteers and donors to understand with which nonprofit to engage and support.
The Theory of Change answers three questions: what is the problem to be solved (including who or what is the focus of the effort and what are the conditions that affect this focus); what approach will be most effective in addressing the problem; and, assuming success, what will be the result.
One example way less complicated of a description that is appropriate to the subject, of "competing" Theories of Change is Planned Parenthood and Birthright. Both institutions believe women's health is important and both institutions understand and support values having to do with childbirth. However, both institutions view the "problem" they seek to address differently AND view the strategies necessary to address the problem differently. Their results, consequentially, sometimes differ. Note though, facts may or may not fully inform the Theory of Change. Values play an equally important role in defining the Theory of Change. Values likely explain why two nonprofits can be engaged in the same field but have such radically different approaches.
Nonprofit boards do well to revisit their Theory of Change at least when they are involved in strategic planning (every 3 or so years). The fundamental values discussed about the board's "world" will inform an understanding of the organization's problem-to-be-solved and subsequently inform intended strategies which in-turn, inform results.
This has been a really simplistic overview but hopefully one that stimulates board's considering the value of their Theory of Change and understanding the so-what as this relates to donors and volunteers.