"demarcation"/"delineation. I'm confused about these differences

The American Heritage Dictionary lists "demarcation" as:

1. The setting or marking of boundaries or limits.
2. A separation; a distinction: a line of demarcation between two rock strata. [Spanish demarcación, from demarcar, to mark boundaries : de-, off (from Latin d¶; see DE) + marcar, to mark (from Italian marcare, from Old Italian, of Germanic origin; see merg- below).]

Whereas Word Net lists "delineation" as:

1: a graphic or vivid verbal description; "too often the narrative was interrupted by long word pictures"; "the author gives a depressing picture of life in Poland"; "the pamphlet contained brief characterizations of famous Vermonters"
2: a drawing of the outlines of forms or objects [syn: {depiction}, {limning}, {line drawing}] 3: representation by drawing or painting etc [syn: {depiction}, {portrayal}]

The main sense of 'demarcation', according to my friends, is about separation of space between boundaries.

The main sense of 'delineation' is about enclosing a space within a boundary. them

Is my friend's review of this word correct or wrong? I am so confused about their differences.