D&D 5E [Spoiler] Spellcasters in Phandelver

[Anth]

In the Starter Set adventure "Lost Mine of Phandelver":
Iarno Albrek is described as a 4th level wizard with CON 11. By the rules he should have 4d6 hp, but he has 5d8.
Nezznar is described as a 4th level wizard with CON 10. By the rules he should have 4d6 hp, but he has 6d8.
Neither the number of hit dice nor the die type is correct.
Can someone explain to me how this works?

 

[jadrax]

In the Starter Set adventure "Lost Mine of Phandelver":
Iarno Albrek is described as a 4th level wizard with CON 11. By the rules he should have 4d6 hp, but he has 5d8.
Nezznar is described as a 4th level wizard with CON 10. By the rules he should have 4d6 hp, but he has 6d8.
Neither the number of hit dice nor the die type is correct.
Can someone explain to me how this works?

NPCs are not built by the same rules as PCs.

 

[wedgeski]

In the Starter Set adventure "Lost Mine of Phandelver":
Iarno Albrek is described as a 4th level wizard with CON 11. By the rules he should have 4d6 hp, but he has 5d8.
Nezznar is described as a 4th level wizard with CON 10. By the rules he should have 4d6 hp, but he has 6d8.
Neither the number of hit dice nor the die type is correct.
Can someone explain to me how this works?

They're not PC's, they're "monsters" of type "evil wizard" or whatever it is (don't have my copy of Phandelver with me).