Clonostachys rosea is a well characterized mycoparasitic fungus with great potential for biocontrol of spreading plant pathogenic fungi, essential for assuring future agricultural sustainability. As genomic sequencing is becoming standard procedure within molecular biology, we aim to review previous phenotypic isolate classifications based on comparative whole genome analysis. We also aim to provide an in-depth investigation into what separates different Clonostachys from other members of the phylogenetic family Bionectriaceae. Phylogenetic tests were performed based on housekeeping genes along with whole-genome sequencing of 10 isolates previously identified as C. rosea strains. We demonstrated that the the majority of these isolates belong to Clonostachys byssicola, Clonostachys chloroleuca and Clonostachys rhizophaga. Additionally, we sequenced a Clonostachys solani isolate. We annotated the genomes of 4 representative isolates of the 10 non-C. rosea isolates along with 10 additional genome assemblies of species across the Clonostachys, Fusarium, Neurospora and Trichoderma for a detailed comparative genomic analysis. By using this approach, we were able to determine inter-species and genera functional differences, that Clonostachys spp. have expanded genome and transporters repertoires, while for example chitinases gene families have contracted, in comparison to Fusarium and Trichorderma. Trichoderma, in contrast, display expanded chitinase homologues. This study sheds more light on the Bionectriaceae family and the evolutionary adaptations between these three genera.