Sometimes small differences in formulations will be mostly irrelevant (oh no, your ibuprofen takes a few extra minutes to absorb, but will 99% absorb under almost all circumstances).
But other times, a new crystalline form exists that you weren’t aware of and destroys your entire ongoing production. Same molecule, but different structure that’s too stable and doesn’t dissolve effectively. See: ritonavir.
Sometimes small differences in formulations will be mostly irrelevant (oh no, your ibuprofen takes a few extra minutes to absorb, but will 99% absorb under almost all circumstances).
But other times, a new crystalline form exists that you weren’t aware of and destroys your entire ongoing production. Same molecule, but different structure that’s too stable and doesn’t dissolve effectively. See: ritonavir.