The phrase "closest comparison" means finding something that is very similar or alike in certain aspects. It is used to identify the most similar thing or person when comparing different options. Full definition
But, if anything, a value - added model would force even closer comparisons of individual students with their peers. (indianapublicmedia.org)
Two of these experiments aim to make and trap anti-hydrogen atoms for close comparison with ordinary hydrogen — a glimpse into the anti-world. (newscientist.com)
The initial release of Samsung Galaxy A 2016 series drew very close comparisons with the then flagship, Samsung Galaxy S6. (nashvillechatterclass.com)