Pfam ..... PSSMs from a mirror of the Pfam-A seed alignment database
Smart .... PSSMs from a mirror of the Smart domain alignment database
Cog .... PSSMs from automatically aligned sequences and sequence fragments classified in the COGs resource, see http://www.ncbi.nlm.nih.gov/COG/new/
Kog .... PSSMs from automatically aligned sequences and sequence fragments classified in the KOGs resource, see http://www.ncbi.nlm.nih.gov/COG/new/
Cdd .... A subset of domains from Smart, Pfam, COG, and cd (alignment models curated at NCBI as part of the CDD project) chosen to reduce redundancy and only represent domains with wide phylogenetic distribution; this is the set that's indexed in NCBI's Entrez