Difference between online and on line

Online=noun(location )He searched online. -As in internet.

on = preposition, line = noun (thing)

Generally, posts are positioned in front of nouns (a, an, the)

The clothing are on THE line. [” The line” refers to a clothes line]

She had her pens in a line. [” in” = preposition, “line” = instructions]

Ms. Johnson had our class line up. [line utilized as a verb]

Articles: a – put before a nonspecific noun “Provide me a pen.”, “Where is a bathroom?”