Ok then, I'll assume the same logic then:

NL is easier than FL because a winning player will win more.

NL is harder than FL because a losing player will lose more.

PL is harder than FL because PL often attracts more serious players.

PL is easier than FL because you you will probably have a lower win/100 in FL vs bad players than in PL vs bad players.

7-card stud is easier than hold'em because a beginning player will make easier to spot mistakes.

Hold 'Em is easier than 7-card stud because when you are new, you're mistakes won't be so visible.

Ok,based on those statements I deduce that:

FL is easier than NL.
NL is easier than FL.
PL is easier than FL.
FL is easier than PL.
7-card stud is easier than hold'em.
Hold'em is easier than 7-card stud.