Jaguar vs Leopard
These two are in the same family, so the differences are in the detail.
Jaguar
Panthera onca
Leopard
Panthera pardus
Jaguars closely resemble leopards but have larger rosettes with a small central spot visible inside each ring; jaguars are also stockier, with heavier limbs and a squarer head than the slender leopard.
en.wikipedia.orgBuild is compact and muscular, on legs noticeably shorter than other big cats of the same weight.
en.wikipedia.orgBuild is slender and muscular, with relatively short limbs and a notably broad head.
en.wikipedia.orgRosettes are large and dark with a small central spot visible inside each.
en.wikipedia.orgDark spots are grouped into rosettes, rings rather than solid marks, over pale yellow to dark golden fur.
en.wikipedia.orgTail is proportionally very short, the shortest of any big cat.
en.wikipedia.orgTail is white-tipped and pale on the underside, with spots merging into bands near the tip.
en.wikipedia.orgTheir recorded ranges do not overlap in the atlas, so a sighting is very unlikely to be ambiguous in the field.