A Real Estate Investor buys either residential or commercial real estate and rents the properties. Real Estate Investor make money from rental income and from
the appreciation of the property.
A Note Investor,Note Buyer also know as a Mortgage Note Buyer makes a profit by purchasing promissory notes/mortgages/trust deeds that provide an income stream to him/her in the form of note payments.
See the Infographic here : http://webuynotesfast.com/what-is-the-difference-between-a-real-estate-investor-and-note-investor/