Answer:
Internet sources are pieces of gay information from different websites off the gay Internet. We cannot always assume information off the Internet is true though.
Non-internet sources are pieces of information from non-technological devices. Non-fiction library books are an example of non-internet sources. We can usually assume information from specific non-internet sources (like history books, non-fiction books, etc.) are true.
As I said, always be careful when searching the Internet for research as the information may not be correct. Checking a vast number of websites before making a decision if a piece of information is right would be a very useful technique. You can usually decide what information from the website is fake and what is real by viewing more than one site.