[Digital-Citizen]

The Unsplash license contains the following:

"This license does not include the right to compile photos from Unsplash to replicate a similar or competing service."

Therefore use "for commercial and noncommercial purposes" is quite restricted to whatever Unsplash considers "a similar or competing service", a vague definition that could change at any time. The medium.com article you pointed to has a bad pointer[1] when it comes to explaining what this means. Unsplash decides what that means ad hoc so you don't really know what your rights are. If what comes under "photos published on Unsplash" could also be considered a computer program, the above quoted clause would render such a program to be nonfree software (see https://www.gnu.org/philosophy/free-sw.html for a definition of free software).

CC0 has no clause comparable to the above quoted clause in the Unsplash license. Also, CC0 is a more thorough abdication of copyright power in copyright regimes where the public domain exists. Unlike the Unsplash license, CC0 uses licensing under a lax, permissive license as a fallback, not a primary mechanism for giving up one's copyright power in the work. This point is not given its due in the medium.com article you pointed us to. Finally, according to https://www.gnu.org/licenses/license-list.html#CC0 CC0 is a non-copyleft free software license when applied to computer software.

[1] https://community.unsplash.com/help-section/what-is-the-unsp... didn't work when I tried it.