What's the difference between manga, manhwa, and manhua? I understand that manga is from Japan and read from right to left, whereas manhwa is from Korea, read from left to right, and manhua is from China, and read from right to left (If I'm not mistaken). Are these the only differences between the three, or is there something else?
What you listed cover many of the major differences, though there are others.

Manga


From Japan
Multi-panel
Almost always black and white
Right-to-left


Manhua


From China
Full color with some panels rendered entirely in painting (1)
Single issue format (1)


Manhwa


From South Korea
Usually horizontal, left-to-right
Can be vertical, right-to-left, top-to-bottom (2)


(1) 

(2)