What's the difference between them?
Affiliate (publisher)
As I signed up for a free CJ (Commission Junction) Affiliate account at www.cj.com, I am the affiliate earning commissions. This is what CJ refers to as a Publisher.
An affiliate can do quite a bit with this free publisher account keeping in mind that there are rules to hold for everyone. the Publisher Service Agreement (PSA) that I agreed to when I signed up. I must also strictly observe the stated terms and conditions of each of the advertisers I promote.
Advertiser (merchant)
Advertisers are called merchants by some affiliate programs.
They are part of a paid program and have a contractual agreement with Commission Junction.
In short, advertisers pay fees to Commission Junction and pay publishers (affiliate) commissions for successful transactions that originate from our marketing/promotional efforts.