The difference between Conversation and Discussion

When used as nouns, conversation means interaction, whereas discussion means conversation or debate concerning a particular topic.

Conversation is also verb with the meaning: to engage in conversation (with).

check bellow for the other definitions of Conversation and Discussion

Conversation as a noun (obsolete):

Interaction; commerce or intercourse with other people; dealing with others.
Conversation as a noun (archaic):

Behaviour, the way one conducts oneself; a person's way of life.
Conversation as a noun (obsolete):

Sexual intercourse.
Conversation as a noun (obsolete):

Engagement with a specific subject, idea, field of study etc.; understanding, familiarity.
Conversation as a noun:

Expression and exchange of individual ideas through talking with other people; also, a set instance or occasion of such talking.

Examples:

"I had an interesting conversation with Nicolas yesterday about how much he's getting paid."
Conversation as a noun (fencing):

The back-and-forth play of the blades in a bout.
Conversation as a noun (computing):

The protocol-based interaction between systems processing a transaction.

Conversation as a verb (nonstandard, ambitransitive):

To engage in conversation (with).

Discussion as a noun:

Conversation or debate concerning a particular topic.

Examples:

"There was then a long discussion of whether to capitalize words like "east"."

"This topic is not open to discussion."

"My discussion with the professor was very enlightening."
Discussion as a noun:

Text giving further detail on a subject.

Examples:

"Under each heading, you will find a discussion."
Discussion as a noun (medicine, obsolete):

The dispersion of a tumour.