Irrespective vs. Irrelevant — What's the Difference?

Heedless, regardless.

Unrelated to the matter being considered.

Without regard for conditions, circumstances, or consequences; unbiased; independent; impartial.

Not relevant, as:

(obsolete) Disrespectful.

Not at all related: totally unrelated, wholly unconnected, completely inapplicable.

Without regard for conditions, circumstances, or consequences; unbiased; independent; impartial; as, an irrespective judgment.

Not usefully related: not associated in any way that is important or useful to the context being discussed: not materially applicable; having connections not applicable in the present situation.

Disrespectful.

Having no bearing on or connection with the subject at issue;

In spite of everything; without regard to drawbacks;