[TriLUG] Fax vs. .pdf - calling all IT gurus

[M. R.]

Special to IT savants:

Is there security basis for preferring faxes to .pdfs attached to emails 
as a method for putting documents (hand-signed or otherwise) into the 
hands of agencies*?

*Agencies: such as brokerage firms, banks, insurance companies, 
government offices, etc.

To my untutored mind faxes and .pdfs are both the output of a document 
scan. The only difference is the mode of delivery. What have I missed 
and how much effort is needed to get the system off its fax-fixation?

Thanks.

Mike R.