Abstract art, nonfigurative art, nonobjective art, and nonrepresentational art are loosely related terms. They are similar, but perhaps not of identical meaning.
Abstraction is a departure from reality in depiction of imagery in art. This departure from accurate representation can be slight, partial, or complete. that aims for verisimilitude of the highest degree can be said to be abstract, at least theoretically, since perfect representation is likely to be exceedingly elusive. Artwork which takes liberties, altering for instance color and form in ways that are conspicuous, can be said to be partially abstract. Total abstraction bears no trace of any reference to anything recognizable.
Both geometric abstraction and lyrical abstraction are often totally abstract. Among numerous art movements that embody partial abstraction would be for instance fauvism in which color is conspicuously and deliberately altered vs reality, and cubism, which blatantly alters the forms of the real life entities depicted.
Contrary to popular belief, abstract art is not just throwing paint onto the canvas. Look at Jean-Paul Riopelle and Jackson Pollock’s paintings, they are systematic and deliberate, nothing is accidental and by chance. Try copying either one of their paintings and you will soon realize how difficult it is. Some even suggested that old masters painting replicas are being churned out in assembly lines in Asia but not so much from Riopelle and Jackson.