Phylogenetics
Diploid thallus vs. haploid or dikaryotic
Heterokont flagella vs. no flagella or simple
Cellulose vs. chitin
Sporopollenin in spore coat, gametophyte dominant, exclusively thalloid
Soft fronds vs xerophytic leaves
Free-living female gametophyte vs retained
Spores vs pollen
2 simple flagella vs heterokont flagella
Multinucleate feeding plasmodium vs diploid filaments
one organism during fruiting vs many organisms together