[Kranar]

There's no formal hierarchy so there's nothing technical about it. Field's medal is certainly prestigious but it's not widely applicable, it has a bunch of restrictions that don't have anything to do with math itself, including an age limit. For example no one who has ever been awarded an Abel Prize would qualify for a Field's medal strictly due to age.

[math_dandy]

Six Abel laureates (out of 22) had previously won the Fields Medal: Serre, Aliyah, Thompson, Milner, Deligne, and Margulis.