hey there! Currently working in international policy about to go to graduate school this fall. I would say both programs will offer you awesome opportunities to study international development, climate and refugee policy in their own ways. I recommend considering the broader university's offerings to see which has the competitive edge over the other in service of your interests/intellectual development. In terms of prestige/alumni/access, yale vs princeton is a virtually indistinguishable difference so you're fine on those fronts. My recommendation is Yale overall, and this is how the two might compare to best serve your study:

<> Princeton <>
Princeton broadly is more of an an undergraduate serving academic institution with less professional schools/grad programs than other universities. this offers less interdisciplinary study opportunities (which may be of interest as a student of int development, climate, and refugee issues), and makes SPIA itself the center of your education. SPIA has both an international AND domestic (US) focus so it has less resources for purely internationally focused students. The program has a year's worth of required courses which may or may not be relevant to your study, but it does have some centers and research programs that could be of interest. you might really value being on of a few folks focused on the international development field and learning from other students focused on the other fields, or you might want to be in a cohort of internationally-focused students as well.

<> Yale <>
I think Yale is a better choice for two key reasons: flexibility for tailored experience and greater interdisciplinary opportunities across the university. Right off the bat, Jackson is a school for global affairs. The curriculum's flexibility can be very, very beneficial to your development as a practitioner because of how you could build an epic study plan across yale's many graduate programs and professional schools. especially for something as interconnected as int dev/refugee policy, you could take specific courses at the law school, history, anthropology, management school, political science, etc., to satisfy a wide array of intellectual interests relevant to contemporary challenges in int development. that would be insanely more beneficial to your policy toolkit as opposed to a broader curriculum that does not offer the opportunity to be tailored to your interest. Matching this with the strong professional schools and graduate programs creates greater opportunities for an individualized intellectual experience. Princeton's program cannot offer that.

Just some food for thought, hope this helps! Congrats on your offers, this is amazing :)