@Chuck it's because they are trying to change the source material (as seen on novelbin) which puts the ranks as:
White = Private
Silver = Leutamemt
Gold = Colonel
Purple = General
Other adjustments are that the scythe doesn't exist, there is no equipment for necromancers (otherwise people would know about the class even if it was never seen before), the general is actually a skill in the novel (summon whight/witch/litch general which allows him to summon a general and place skeletons and skele mages under it's controll and he can summon more for his storage. Additionally when he levels it up he gets to where he can have 10 generals with hundreds of skeletons under the control of each general, as well as his own troops filling his storage with the 10 generals only counting for 10 spots while they each controll 200 warriors and 100 mages that don't count against his storage,)
Oh and he can't control boss monsters, they got that from solo leveling to make him "less overpowering" and "more interesting".
White = Private
Silver = Leutamemt
Gold = Colonel
Purple = General
Other adjustments are that the scythe doesn't exist, there is no equipment for necromancers (otherwise people would know about the class even if it was never seen before), the general is actually a skill in the novel (summon whight/witch/litch general which allows him to summon a general and place skeletons and skele mages under it's controll and he can summon more for his storage. Additionally when he levels it up he gets to where he can have 10 generals with hundreds of skeletons under the control of each general, as well as his own troops filling his storage with the 10 generals only counting for 10 spots while they each controll 200 warriors and 100 mages that don't count against his storage,)
Oh and he can't control boss monsters, they got that from solo leveling to make him "less overpowering" and "more interesting".