The question is not "what is the difference between hmmscan and pfamscan" and I am sure you just copy pasted the line "PfamScan is used to search a FASTA sequence against a library of Pfam HMM." from this link http://www.ebi.ac.uk/Tools/pfa/pfamscan/
If you are unsure about the question or if you have not really worked on the type of problem, put your thoughts in comments section.