what makes a comic look like a comic instead of just a painting?

Comic is line art. Painting is paint.
(obviously :P)

To put it another way: there are black outlines surrounding blocks of color, or delineating characters, objects, etc. And there are no sound effect words (bam, pow, kablooie, etc.) or word balloons in paintings.

There is pop art.

@taby , the question is:

Komatsu said:
what makes a comic look like a comic instead of just a painting?

Pop art pieces are a narrow niche of “paintings.” Pop art is a painting made to look like a comic. So what tricks were used to make pop art look like not just another painting but a comic instead?

Tom Sloper said:
black outlines

And sometimes pointillistic Ben-Day dots, made to resemble the way comics were printed in color. But the question isn't about pop art but about comics and their unique look.

taby said:
There is pop art.

There are also comics made from CGI or other techniques, so the line art property may not hold in every single case for comics either. We can answer only broadly for the general case.

Thanks everyone. It seems that the inking process has much to do with it gathering what everyone has said.

Comico and Marvel Epic both did away with the Ben-Day process. For instance, the North American version of Akira was printed using full colour, done on a computer. Grendel was also a trendsetter. This is back in the late 80s and early 90s.

taby said:
Comico and Marvel Epic both did away with the Ben-Day process.

That does not help the original question, which was:

Komatsu said:
what makes a comic look like a comic instead of just a painting?

Well, it probably won't help either, but there is also Art Nouveau.