Difference between Unreasonable and Undue

UNREASONABLE vs UNDUE: ADJECTIVE

Not yet payable
Not appropriate or proper (or even legal) in the circumstances
Beyond normal limits
Exceeding what is appropriate or normal; excessive.
Not just, proper, or legal.
Not due; not yet owing.
Not right; not lawful or legal; improper.
Not agreeable to a rule or standard, or to duty; disproportioned; excessive; immoderate; inordinate.
Any improper or wrongful constraint, machination, or urgency of persuasion, by which one's will is overcome and he is induced to do or forbear an act which he would not do, or would do, if left to act freely.
Excessive; going beyond that what is natural or sufficient.
That which ought not to be done; illegal; unjustified.
Not owing or payable.
Lacking justification or authorization

Not showing good judgment
Synonyms Absurd, Silly, Foolish, etc. (see absurd), obstinate, wrong-headed, extravagant, unfair, unjust, extortionate.
Inconvenient.
Not listening to or acting according to reason; not guided by reason; not influenced by reason.
Not endowed with reason; irrational.
Exceeding the bounds of reason; beyond what is reasonable or moderate; exorbitant; immoderate: as, an unreasonable price.
Not reasonable or agreeable to reason; irrational.

Not due; not yet demandable by right; not yet owing: as, a debt, note, or bond undue.
Erring by excess; excessive; inordinate; disproportioned: as, an undue regard to the externals of religion; an undue attachment to forms; an undue rigor in the execution of law.
Not right; not lawful; improper; unworthy: as, an undue proceeding.

Senseless, Incongruous, Silly, Indefensible, Inordinate, Undue, Foolish, Untenable, Excessive, Absurd, Irrational, Illogical, Unrealistic, Unjustified, Unwarranted

Reasonable, Exorbitant, Undesirable, Unjustifiable, Needless, Disproportionate, Unfair, Unnecessary, Not due, Immoderate, Unjustified, Unreasonable, Excessive, Inordinate, Unwarranted

Senseless, Incongruous, Silly, Indefensible, Inordinate, Undue, Foolish, Untenable, Excessive, Absurd, Irrational, Illogical, Unrealistic, Unjustified, Unwarranted

Reasonable, Exorbitant, Undesirable, Unjustifiable, Needless, Disproportionate, Unfair, Unnecessary, Not due, Immoderate, Unjustified, Unreasonable, Excessive, Inordinate, Unwarranted

Disarm unreasonable and difficult behavior when correctly used.
Therefore all progress depends on the unreasonable man.
An attorney shall not make an agreement for, charge, or collect an unreasonable fee or an unreasonable amount for expenses.
It would, for example be unreasonable to insist on compliance with the clause if it was unreasonable or impossible for the person to comply.
Whether a behaviour is unreasonable can depend on whether a reasonable person might see the behaviour as unreasonable in the circumstances.
Charter arguments, such as unreasonable delay, the right to be secure against unreasonable search and seizure, and the right to counsel.
You can definitely sue for unreasonable delays if you can prove that the delays are, in fact, unreasonable.
The traveller complained that the arrest was unreasonable and that various actions of the involved police officers were unreasonable.
An unreasonable comprehensive doctrine is unreasonable in the sense that it is incompatible with the duty of civility.
The Right Against Unreasonable Search and Seizure The Fourth Amendment protects persons from unreasonable searches and seizures.

Denial of Medicaid would cause an UNDUE HARDSHIP.
Subjects the recipient to undue burden or expense.
University academic regulation or policy causes undue hardship.
This obligation is limited only by undue hardship.
The remaining incidents of undue discretion alleged by ATA were not preserved for appeal and do not otherwise confer the Director with undue discretion.
Incomeshifting also leads to an undue reduction of the tax base in onecountry with a corresponding undue tax base increase in another.
Court for protective order to prevent undue annoyance, harassment, embarrassment, oppression, or undue burden or expense, and the Court maproceed only upon specified conditions.
Children of believers are to be baptised without undue delay, but without undue haste.
Techniques of communication which intimidate, exert undue pressure or undue influence over a prospective client.
Undue influence: types of undue influence, how can a bank protect its transactions from challenge on the grounds of undue influence?