So, there is a thing in art history called “Net Art”, “Internet art” etc. People do write books about this. This is not the kind of art I want to discuss on this site.
Net art is very much about the internet, about the technology, etc. It has a lot in common with contemporary art: it is often abstract or nonrepresentational, it often comments on political or social issues. It often tries to be immersive, or interactive. It almost always involves the technology used to create it as an integral part of the artwork. It often involves the artist trying to do something new via hacking, programming, etc. It tends to be created by professional artists.
Art in internet culture is quite different. It is primarily created by amateur artists, it is mostly but not always digital, and the goal is generally to create a nice looking picture. I think one of the most significant differences between net art and internet culture art is that art in internet culture is not obsessed with technology. It is a tool to create and share the artwork, but it is not integral to the artwork. While art in internet culture can tackle political/social issues, most art does not do this. Fanart is very common.