This review in 2015 outlines the cellular physiology of each form of B12 and where each form is stored, as well as the potential therapeutic action of each.
References:
Thakkar, K. and Billa, G. Treatment of vitamin B12 deficiency-Methylcobalamine? Cyancobalamine? Hydroxocobalamin?—clearing the confusion European Journal of Clinical Nutrition (2015) 69, 1–2. https://pubmed.ncbi.nlm.nih.gov/25117994/