Two men of the same height... why does one still look more defined and solid even while having a higher body-fat percentage?

You didn't say they're the same weight.

One could legitimately be more muscular, and equally fat. For example a typical builder or brick layer who frequently eats in cafes and snacks of biscuits, but has a manually intensive job.

The other could be almost non existent muscularity, but also fat, and rarely exercises, but may still fit in to normal sizes clothes and not appear obese despite having a healthy bmi can still be overweight. Typically they're have a bmi of about 23% but carry 30% body fat, typically an office worker with no exercise and drives\sits in front of the tv or computer all day. This is what "skinny fat" means, means you eat 2500 calories a day of junk and don't move around much at all.

Mostly because of genes. Also, very few of these body-fat calculations are correct. There is a general margin that changes, and it also depends a lot on what time of day you do this test. Maybe the differences arent as big as one would think. Thirdly, if the two persons you are comparing are one skinny guy with <10% bf, and the other one is a guy who have worked out, but with a bit higher body fat percentage, he could still look more masculine. Its a lot of factors to put into this, low body fat doesnt automatically make a guy handsome.

Higher muscle tone will cause this.

A fatter man (or woman) may be stronger, but without having larger muscles, because higher tone increases their density too.

These harder muscles keep their shape during movement and relaxation, more than softer muscles do.

This makes them look more defined, even through a thicker layer of fat.

Height is unrelated to bodyfat, and does not affect definition.

yeh sure.. called genetics. .

that was easy.