The suffixes ‘-er’   / ‘-or’
  ‘-er’ or ‘-or’ is added to some verbs to form nouns that refer to people or things connected  to a particular activity.
Verb/Noun  | 
                  Noun  | 
                  Meaning  | 
                
produce  | 
                  producer  | 
                  a person who creates something or brings into existence  | 
                
manufacture  | 
                  manufacturer  | 
                  a person who produces goods in large numbers,   | 
                
retail  | 
                  retailer  | 
                  a person who sells goods to the public, usually in small amounts, for personal use  | 
                
transport  | 
                  transporter  | 
                  a person who takes goods or people from one place to another  | 
                
wholesale  | 
                  wholesaler  | 
                  a person who sells goods, usually in large amounts, to businesses which then sell them to the public  | 
                
distribute  | 
                  distributor  | 
                  an agent who supplies goods to retailers  | 
                
process  | 
                  processor  | 
                  a machine or person that processes something  |